Implemented pthread_atfork()

Change-Id: Ie6c0bf593315d3507b3c4a6c8903a74a1fa053db
diff --git a/libc/bionic/pthread_internal.h b/libc/bionic/pthread_internal.h
index eb4e80c..655b8f3 100644
--- a/libc/bionic/pthread_internal.h
+++ b/libc/bionic/pthread_internal.h
@@ -109,6 +109,9 @@
 
 /* needed by fork.c */
 extern void __timer_table_start_stop(int  stop);
+extern void __bionic_atfork_run_prepare();
+extern void __bionic_atfork_run_child();
+extern void __bionic_atfork_run_parent();
 
 __END_DECLS