Add C11 timespec_get.

Bug: https://github.com/android-ndk/ndk/issues/744
Test: ran tests
Change-Id: Iad9514946e06d55b6a3aa0f945d9a63bff900881
diff --git a/libc/libc.arm64.map b/libc/libc.arm64.map
index b7f7c89..3e20d7e 100644
--- a/libc/libc.arm64.map
+++ b/libc/libc.arm64.map
@@ -1344,6 +1344,7 @@
 LIBC_Q { # introduced=Q
   global:
     __res_randomid;
+    timespec_get;
 } LIBC_P;
 
 LIBC_PRIVATE {