Refresh 64-bit headers/libs (WW21)

Change-Id: I013af3ae4adac17d7b2ef5680d41d75dc9799d19

ndk/platforms/android-20/include/sys/cdefs.h

@@ -37,6 +37,24 @@
 #ifndef	_SYS_CDEFS_H_
 #define	_SYS_CDEFS_H_
 
+/*
+ * Testing against Clang-specific extensions.
+ */
+
+#ifndef __has_extension
+#define __has_extension         __has_feature
+#endif
+#ifndef __has_feature
+#define __has_feature(x)        0
+#endif
+#ifndef __has_include
+#define __has_include(x)        0
+#endif
+#ifndef __has_builtin
+#define __has_builtin(x)        0
+#endif
+
+
 /*
  * Macro to test if we're using a GNU C compiler of a specific vintage
  * or later, for e.g. features that appeared in a particular version