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/__cxa_thread_atexit_impl.cpp b/libc/bionic/__cxa_thread_atexit_impl.cpp
index 6284b12..f687fd1 100644
--- a/libc/bionic/__cxa_thread_atexit_impl.cpp
+++ b/libc/bionic/__cxa_thread_atexit_impl.cpp
@@ -15,6 +15,8 @@
  */
 #include <sys/cdefs.h>
 
+#include <private/bionic_defs.h>
+
 #include "pthread_internal.h"
 
 class thread_local_dtor {
@@ -25,7 +27,10 @@
   thread_local_dtor* next;
 };
 
-extern "C" int __cxa_thread_atexit_impl(void (*func) (void *), void *arg, void *dso_handle) {
+extern "C" int __cxa_thread_atexit_impl(void (*func) (void *), void *arg, void *dso_handle);
+
+__BIONIC_WEAK_FOR_NATIVE_BRIDGE
+int __cxa_thread_atexit_impl(void (*func) (void *), void *arg, void *dso_handle) {
   thread_local_dtor* dtor = new thread_local_dtor();
 
   dtor->func = func;