Nico Rieck:  Currently _MSC_VER and _WIN32 are used to guard code which is
MSVC-specific, MSVCRT-specific, or Windows-specific. Because Clang can
also define _MSC_VER, and MSVCRT is not necessarily the only C runtime,
these macros should not be used interchangeably.

This patch divides all Windows-related bits into the aforementioned
categories. Two new macros are introduced:

- _LIBCPP_MSVC: Defined when compiling with MSVC. Detected using
  _MSC_VER, excluding Clang.
- _LIBCPP_MSVCRT: Defined when using the Microsoft CRT. This is the default
   when _WIN32 is defined.

This leaves _WIN32 for code using the Windows API.

This also corrects the spelling of _LIBCP_HAS_IS_BASE_OF to _LIBCPP_HAS_IS_BASE_OF.

Nico, please prepare a patch for CREDITS.TXT, thanks.

git-svn-id: https://llvm.org/svn/llvm-project/libcxx/trunk@187593 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/include/cwchar b/include/cwchar
index 845ccec..90eae75 100644
--- a/include/cwchar
+++ b/include/cwchar
@@ -106,9 +106,9 @@
 #include <__config>
 #include <cwctype>
 #include <wchar.h>
-#ifdef _WIN32
+#ifdef _LIBCPP_MSVCRT
 #include <support/win32/support.h> // pull in *swprintf defines
-#endif // _WIN32
+#endif // _LIBCPP_MSVCRT
 
 #if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
 #pragma GCC system_header
@@ -127,12 +127,12 @@
 using ::vfwprintf;
 using ::vswprintf;
 using ::vwprintf;
-#ifndef _MSC_VER
+#ifndef _LIBCPP_MSVCRT
 using ::swscanf;
 using ::vfwscanf;
 using ::vswscanf;
 using ::vwscanf;
-#endif // _MSC_VER
+#endif // _LIBCPP_MSVCRT
 using ::wprintf;
 using ::wscanf;
 using ::fgetwc;
@@ -146,10 +146,10 @@
 using ::putwchar;
 using ::ungetwc;
 using ::wcstod;
-#ifndef _MSC_VER
+#ifndef _LIBCPP_MSVCRT
 using ::wcstof;
 using ::wcstold;
-#endif // _MSC_VER
+#endif // _LIBCPP_MSVCRT
 using ::wcstol;
 #ifndef _LIBCPP_HAS_NO_LONG_LONG
 using ::wcstoll;