Mark __BIONIC_WEAK_FOR_NATIVE_BRIDGE symbols

To make it easier for Native Bridge implementations
to override these symbols.

Bug: http://b/67993967
Test: make
Change-Id: I4c53e53af494bca365dd2b3305ab0ccc2b23ba44
diff --git a/libc/bionic/pthread_create.cpp b/libc/bionic/pthread_create.cpp
index 11e148c..40db785 100644
--- a/libc/bionic/pthread_create.cpp
+++ b/libc/bionic/pthread_create.cpp
@@ -37,6 +37,7 @@
 
 #include <async_safe/log.h>
 
+#include "private/bionic_defs.h"
 #include "private/bionic_macros.h"
 #include "private/bionic_prctl.h"
 #include "private/bionic_ssp.h"
@@ -258,6 +259,8 @@
   return NULL;
 }
 
+
+__BIONIC_WEAK_FOR_NATIVE_BRIDGE
 int pthread_create(pthread_t* thread_out, pthread_attr_t const* attr,
                    void* (*start_routine)(void*), void* arg) {
   ErrnoRestorer errno_restorer;