Add CtsIcu4cTestCases for ICU4C API coverage - Attempt 2

Attempt 2: The test is only for primary ABI, until the Soong limitation
is resolved.
- cintltest and intltest are the executable binaries
  running the devices.
- cintltest and intltest are basically compiled against
  libicuuc and libicui18n, except if the APIs are available
  in the NDK surface in libicu, the test will link that in favour
  of NDK. So the APIs provided in the NDK will have the API coverge,
  while the test can keep using the hidden APIs in libicuuc, and
  libicui18n.
  cts_headers/ are the same as libicuuc and libicui18n headers, except
  that unicode/urename.h is modified by the generate_ndk.py to select
  the NDK API surface.

Bug: 160350521
Test: atest CtsIcu4cTestCases
Test: Inspect the symbol table manually by "objdump -TC cintltst"
Test: build/soong/build_test.bash
Test: Test: OUT_DIR=ndk_out build/soong/scripts/build-ndk-prebuilts.sh
Change-Id: Icf51b09c36eb3b4ef30a5032bdef7af1a76567d9
diff --git a/libicu/cts_headers/unicode/localebuilder.h b/libicu/cts_headers/unicode/localebuilder.h
new file mode 100644
index 0000000..19e10f1
--- /dev/null
+++ b/libicu/cts_headers/unicode/localebuilder.h
@@ -0,0 +1,315 @@
+// © 2018 and later: Unicode, Inc. and others.
+// License & terms of use: http://www.unicode.org/copyright.html#License
+#ifndef __LOCALEBUILDER_H__
+#define __LOCALEBUILDER_H__
+
+#include "unicode/utypes.h"
+
+#if U_SHOW_CPLUSPLUS_API
+
+#include "unicode/locid.h"
+#include "unicode/localematcher.h"
+#include "unicode/stringpiece.h"
+#include "unicode/uobject.h"
+
+#ifndef U_HIDE_DRAFT_API
+/**
+ * \file
+ * \brief C++ API: Builder API for Locale
+ */
+
+U_NAMESPACE_BEGIN
+class CharString;
+
+/**
+ * <code>LocaleBuilder</code> is used to build instances of <code>Locale</code>
+ * from values configured by the setters.  Unlike the <code>Locale</code>
+ * constructors, the <code>LocaleBuilder</code> checks if a value configured by a
+ * setter satisfies the syntax requirements defined by the <code>Locale</code>
+ * class.  A <code>Locale</code> object created by a <code>LocaleBuilder</code> is
+ * well-formed and can be transformed to a well-formed IETF BCP 47 language tag
+ * without losing information.
+ *
+ * <p>The following example shows how to create a <code>Locale</code> object
+ * with the <code>LocaleBuilder</code>.
+ * <blockquote>
+ * <pre>
+ *     UErrorCode status = U_ZERO_ERROR;
+ *     Locale aLocale = LocaleBuilder()
+ *                          .setLanguage("sr")
+ *                          .setScript("Latn")
+ *                          .setRegion("RS")
+ *                          .build(status);
+ *     if (U_SUCCESS(status)) {
+ *       // ...
+ *     }
+ * </pre>
+ * </blockquote>
+ *
+ * <p>LocaleBuilders can be reused; <code>clear()</code> resets all
+ * fields to their default values.
+ *
+ * <p>LocaleBuilder tracks errors in an internal UErrorCode. For all setters,
+ * except setLanguageTag and setLocale, LocaleBuilder will return immediately
+ * if the internal UErrorCode is in error state.
+ * To reset internal state and error code, call clear method.
+ * The setLanguageTag and setLocale method will first clear the internal
+ * UErrorCode, then track the error of the validation of the input parameter
+ * into the internal UErrorCode.
+ *
+ * @draft ICU 64
+ */
+class U_COMMON_API LocaleBuilder : public UObject {
+public:
+    /**
+     * Constructs an empty LocaleBuilder. The default value of all
+     * fields, extensions, and private use information is the
+     * empty string.
+     *
+     * @draft ICU 64
+     */
+    LocaleBuilder();
+
+    /**
+     * Destructor
+     * @draft ICU 64
+     */
+    virtual ~LocaleBuilder();
+
+    /**
+     * Resets the <code>LocaleBuilder</code> to match the provided
+     * <code>locale</code>.  Existing state is discarded.
+     *
+     * <p>All fields of the locale must be well-formed.
+     * <p>This method clears the internal UErrorCode.
+     *
+     * @param locale the locale
+     * @return This builder.
+     *
+     * @draft ICU 64
+     */
+    LocaleBuilder& setLocale(const Locale& locale);
+
+    /**
+     * Resets the LocaleBuilder to match the provided
+     * [Unicode Locale Identifier](http://www.unicode.org/reports/tr35/tr35.html#unicode_locale_id) .
+     * Discards the existing state. the empty string cause the builder to be
+     * reset, like {@link #clear}.  Grandfathered tags are converted to their
+     * canonical form before being processed.  Otherwise, the <code>language
+     * tag</code> must be well-formed, or else the build() method will later
+     * report an U_ILLEGAL_ARGUMENT_ERROR.
+     *
+     * <p>This method clears the internal UErrorCode.
+     *
+     * @param tag the language tag, defined as
+     *   [unicode_locale_id](http://www.unicode.org/reports/tr35/tr35.html#unicode_locale_id).
+     * @return This builder.
+     * @draft ICU 64
+     */
+    LocaleBuilder& setLanguageTag(StringPiece tag);
+
+    /**
+     * Sets the language.  If <code>language</code> is the empty string, the
+     * language in this <code>LocaleBuilder</code> is removed. Otherwise, the
+     * <code>language</code> must be well-formed, or else the build() method will
+     * later report an U_ILLEGAL_ARGUMENT_ERROR.
+     *
+     * <p>The syntax of language value is defined as
+     * [unicode_language_subtag](http://www.unicode.org/reports/tr35/tr35.html#unicode_language_subtag).
+     *
+     * @param language the language
+     * @return This builder.
+     * @draft ICU 64
+     */
+    LocaleBuilder& setLanguage(StringPiece language);
+
+    /**
+     * Sets the script. If <code>script</code> is the empty string, the script in
+     * this <code>LocaleBuilder</code> is removed.
+     * Otherwise, the <code>script</code> must be well-formed, or else the build()
+     * method will later report an U_ILLEGAL_ARGUMENT_ERROR.
+     *
+     * <p>The script value is a four-letter script code as
+     * [unicode_script_subtag](http://www.unicode.org/reports/tr35/tr35.html#unicode_script_subtag)
+     * defined by ISO 15924
+     *
+     * @param script the script
+     * @return This builder.
+     * @draft ICU 64
+     */
+    LocaleBuilder& setScript(StringPiece script);
+
+    /**
+     * Sets the region.  If region is the empty string, the region in this
+     * <code>LocaleBuilder</code> is removed. Otherwise, the <code>region</code>
+     * must be well-formed, or else the build() method will later report an
+     * U_ILLEGAL_ARGUMENT_ERROR.
+     *
+     * <p>The region value is defined by
+     *  [unicode_region_subtag](http://www.unicode.org/reports/tr35/tr35.html#unicode_region_subtag)
+     * as a two-letter ISO 3166 code or a three-digit UN M.49 area code.
+     *
+     * <p>The region value in the <code>Locale</code> created by the
+     * <code>LocaleBuilder</code> is always normalized to upper case.
+     *
+     * @param region the region
+     * @return This builder.
+     * @draft ICU 64
+     */
+    LocaleBuilder& setRegion(StringPiece region);
+
+    /**
+     * Sets the variant.  If variant is the empty string, the variant in this
+     * <code>LocaleBuilder</code> is removed.  Otherwise, the <code>variant</code>
+     * must be well-formed, or else the build() method will later report an
+     * U_ILLEGAL_ARGUMENT_ERROR.
+     *
+     * <p><b>Note:</b> This method checks if <code>variant</code>
+     * satisfies the
+     * [unicode_variant_subtag](http://www.unicode.org/reports/tr35/tr35.html#unicode_variant_subtag)
+     * syntax requirements, and normalizes the value to lowercase letters. However,
+     * the <code>Locale</code> class does not impose any syntactic
+     * restriction on variant. To set an ill-formed variant, use a Locale constructor.
+     * If there are multiple unicode_variant_subtag, the caller must concatenate
+     * them with '-' as separator (ex: "foobar-fibar").
+     *
+     * @param variant the variant
+     * @return This builder.
+     * @draft ICU 64
+     */
+    LocaleBuilder& setVariant(StringPiece variant);
+
+    /**
+     * Sets the extension for the given key. If the value is the empty string,
+     * the extension is removed.  Otherwise, the <code>key</code> and
+     * <code>value</code> must be well-formed, or else the build() method will
+     * later report an U_ILLEGAL_ARGUMENT_ERROR.
+     *
+     * <p><b>Note:</b> The key ('u') is used for the Unicode locale extension.
+     * Setting a value for this key replaces any existing Unicode locale key/type
+     * pairs with those defined in the extension.
+     *
+     * <p><b>Note:</b> The key ('x') is used for the private use code. To be
+     * well-formed, the value for this key needs only to have subtags of one to
+     * eight alphanumeric characters, not two to eight as in the general case.
+     *
+     * @param key the extension key
+     * @param value the extension value
+     * @return This builder.
+     * @draft ICU 64
+     */
+    LocaleBuilder& setExtension(char key, StringPiece value);
+
+    /**
+     * Sets the Unicode locale keyword type for the given key. If the type
+     * StringPiece is constructed with a nullptr, the keyword is removed.
+     * If the type is the empty string, the keyword is set without type subtags.
+     * Otherwise, the key and type must be well-formed, or else the build()
+     * method will later report an U_ILLEGAL_ARGUMENT_ERROR.
+     *
+     * <p>Keys and types are converted to lower case.
+     *
+     * <p><b>Note</b>:Setting the 'u' extension via {@link #setExtension}
+     * replaces all Unicode locale keywords with those defined in the
+     * extension.
+     *
+     * @param key the Unicode locale key
+     * @param type the Unicode locale type
+     * @return This builder.
+     * @draft ICU 64
+     */
+    LocaleBuilder& setUnicodeLocaleKeyword(
+        StringPiece key, StringPiece type);
+
+    /**
+     * Adds a unicode locale attribute, if not already present, otherwise
+     * has no effect.  The attribute must not be empty string and must be
+     * well-formed or U_ILLEGAL_ARGUMENT_ERROR will be set to status
+     * during the build() call.
+     *
+     * @param attribute the attribute
+     * @return This builder.
+     * @draft ICU 64
+     */
+    LocaleBuilder& addUnicodeLocaleAttribute(StringPiece attribute);
+
+    /**
+     * Removes a unicode locale attribute, if present, otherwise has no
+     * effect.  The attribute must not be empty string and must be well-formed
+     * or U_ILLEGAL_ARGUMENT_ERROR will be set to status during the build() call.
+     *
+     * <p>Attribute comparison for removal is case-insensitive.
+     *
+     * @param attribute the attribute
+     * @return This builder.
+     * @draft ICU 64
+     */
+    LocaleBuilder& removeUnicodeLocaleAttribute(StringPiece attribute);
+
+    /**
+     * Resets the builder to its initial, empty state.
+     * <p>This method clears the internal UErrorCode.
+     *
+     * @return this builder
+     * @draft ICU 64
+     */
+    LocaleBuilder& clear();
+
+    /**
+     * Resets the extensions to their initial, empty state.
+     * Language, script, region and variant are unchanged.
+     *
+     * @return this builder
+     * @draft ICU 64
+     */
+    LocaleBuilder& clearExtensions();
+
+    /**
+     * Returns an instance of <code>Locale</code> created from the fields set
+     * on this builder.
+     * If any set methods or during the build() call require memory allocation
+     * but fail U_MEMORY_ALLOCATION_ERROR will be set to status.
+     * If any of the fields set by the setters are not well-formed, the status
+     * will be set to U_ILLEGAL_ARGUMENT_ERROR. The state of the builder will
+     * not change after the build() call and the caller is free to keep using
+     * the same builder to build more locales.
+     *
+     * @return a new Locale
+     * @draft ICU 64
+     */
+    Locale build(UErrorCode& status);
+
+#ifndef U_HIDE_DRAFT_API
+    /**
+     * Sets the UErrorCode if an error occurred while recording sets.
+     * Preserves older error codes in the outErrorCode.
+     * @param outErrorCode Set to an error code that occurred while setting subtags.
+     *                  Unchanged if there is no such error or if outErrorCode
+     *                  already contained an error.
+     * @return TRUE if U_FAILURE(outErrorCode)
+     * @draft ICU 65
+     */
+    UBool copyErrorTo(UErrorCode &outErrorCode) const;
+#endif  /* U_HIDE_DRAFT_API */
+
+private:
+    friend class LocaleMatcher::Result;
+
+    void copyExtensionsFrom(const Locale& src, UErrorCode& errorCode);
+
+    UErrorCode status_;
+    char language_[9];
+    char script_[5];
+    char region_[4];
+    CharString *variant_;  // Pointer not object so we need not #include internal charstr.h.
+    icu::Locale *extensions_;  // Pointer not object. Storage for all other fields.
+
+};
+
+U_NAMESPACE_END
+
+#endif  // U_HIDE_DRAFT_API
+
+#endif /* U_SHOW_CPLUSPLUS_API */
+
+#endif  // __LOCALEBUILDER_H__