Move Java9LanguageFeaturesTest into its own directory.

This is in preparation for http://r.android.com/999933, which adds
more build file complexity around this test, and means that complexity
is kept out of the top-level libcore JavaLibrary.bp.

Test: cts-tradefed run cts-dev -m CtsLibcoreTestCase -t libcore.libcore.internal

Change-Id: I31bb233925cfb39c0654b0af0813b33b26527787
diff --git a/JavaLibrary.bp b/JavaLibrary.bp
index 75eee87..ac394b4 100644
--- a/JavaLibrary.bp
+++ b/JavaLibrary.bp
@@ -145,6 +145,7 @@
     "//external/icu/android_icu4j",
     "//external/okhttp",
     "//libcore/benchmarks",
+    "//libcore/luni/src/test/java9language",
     "//libcore/mmodules/intracoreapi",
 ]
 
@@ -535,6 +536,7 @@
 
     static_libs: [
         "archive-patcher",
+        "core-java-9-language-tests",
         "core-test-rules",
         "core-tests-support",
         "junit-params",