Revert "Revert "Remove incorrect android_atomic_...64 use.""

This reverts commit 9dc5c269f74ac76f62515e3d9558e67c6e63067d.
Adds a stdint.h include in case stdatomic.h stops including that.

Change-Id: If3dd1db1f1132c0f2dc1efb0a44617d3f36d7cfb
diff --git a/include/binder/Binder.h b/include/binder/Binder.h
index ba3ac4b..86628a0 100644
--- a/include/binder/Binder.h
+++ b/include/binder/Binder.h
@@ -17,6 +17,8 @@
 #ifndef ANDROID_BINDER_H
 #define ANDROID_BINDER_H
 
+#include <stdatomic.h>
+#include <stdint.h>
 #include <binder/IBinder.h>
 
 // ---------------------------------------------------------------------------
@@ -69,7 +71,7 @@
 
     class Extras;
 
-            Extras*     mExtras;
+    atomic_uintptr_t    mExtras;  // should be atomic<Extras *>
             void*       mReserved0;
 };