Remove unnecessary 'extern's.

Change-Id: Iba2b3fb6ff88e504f1657b915120ae43d58a1e03
diff --git a/libc/include/sys/times.h b/libc/include/sys/times.h
index 6ce5b55..f52db1f 100644
--- a/libc/include/sys/times.h
+++ b/libc/include/sys/times.h
@@ -35,7 +35,7 @@
 
 __BEGIN_DECLS
 
-extern clock_t times(struct tms*);
+clock_t times(struct tms*);
 
 __END_DECLS