Fix pthread_cleanup_push() to new API after rebase.

src/library_pthread.js

@@ -622,7 +622,7 @@ var LibraryPThread = {
     if (PThread.exitHandlers === null) {
       PThread.exitHandlers = [];
       if (!ENVIRONMENT_IS_PTHREAD) {
-        __ATEXIT__.push({ func: function() { PThread.runExitHandlers(); } });
+        __ATEXIT__.push(function() { PThread.runExitHandlers(); });
       }
     }
     PThread.exitHandlers.push(function() { Runtime.dynCall('vi', routine, [arg]) });

src/library_pthread_stub.js

@@ -102,7 +102,7 @@ var LibraryPThreadStub = {
   },
 
   pthread_cleanup_push: function(routine, arg) {
-    __ATEXIT__.push({ func: function() { Runtime.dynCall('vi', routine, [arg]) } })
+    __ATEXIT__.push(function() { Runtime.dynCall('vi', routine, [arg]) })
     _pthread_cleanup_push.level = __ATEXIT__.length;
   },