Update 64-bit headers/libs

Also
1) rename lib -> lib64
2) add src/ for android-20/arch-arm64 and arch-mips64
3) delete android-9/arch-arm64 and arch-mips64

Change-Id: I4958c4e52946e29e57b910f39ff0104200853a06

ndk/platforms/android-20/include/limits.h

@@ -105,6 +105,15 @@
 #define ULONG_LONG_MAX  ULLONG_MAX
 #endif
 
+/* BSD compatibility definitions. */
+#if __BSD_VISIBLE
+#define SIZE_T_MAX ULONG_MAX
+#endif /* __BSD_VISIBLE */
+
+#define SSIZE_MAX LONG_MAX
+
+#define MB_LEN_MAX 1 /* No multibyte characters. */
+
 /* New code should use sysconf(_SC_PAGE_SIZE) instead. */
 #ifndef PAGE_SIZE
 #define PAGE_SIZE 4096