Add C11 timespec_get.

Bug: https://github.com/android-ndk/ndk/issues/744
Test: ran tests
Change-Id: Iad9514946e06d55b6a3aa0f945d9a63bff900881
diff --git a/libc/include/time.h b/libc/include/time.h
index 17751d7..ea41fda 100644
--- a/libc/include/time.h
+++ b/libc/include/time.h
@@ -108,6 +108,9 @@
 time_t timelocal(struct tm* __tm) __INTRODUCED_IN(12);
 time_t timegm(struct tm* __tm) __INTRODUCED_IN(12);
 
+#define TIME_UTC 1
+int timespec_get(struct timespec* __ts, int __base) __INTRODUCED_IN_FUTURE;
+
 __END_DECLS
 
 #endif