[android] Fix issue when stop is called before run on the RunLoop

The current ::stop() implementation was not thread safe and we
should queue the ::stop() for the next loop iteration so even
if we call ::stop() before ::run(), it gets processed.

platform/android/src/run_loop.cpp

@@ -211,8 +211,10 @@ void RunLoop::runOnce() {
 }
 
 void RunLoop::stop() {
-    impl->running = false;
-    impl->wake();
+    invoke([&] {
+        impl->running = false;
+        impl->wake();
+    });
 }
 
 void RunLoop::addWatch(int, Event, std::function<void(int, Event)>&&) {