Use ALooper_pollOnce instead of ALooper_pollAll

pollAll is marked for deletion in AOSP so it won't eventually be
callable in future NDKs. There should be no practical differences
except that we should be free of
android/ndk#2020

app/src/main/cpp/native-lib.cpp

@@ -207,7 +207,7 @@ android_main(android_app *aAppState) {
     android_poll_source *pSource;
 
     // Loop until all events are read. If the activity is paused use a blocking call to read events.
-    while (ALooper_pollAll(computeALooperTimeout(), nullptr, &events, (void **) &pSource) >= 0) {
+    while (ALooper_pollOnce(computeALooperTimeout(), nullptr, &events, (void **) &pSource) >= 0) {
       // Process event.
       if (pSource) {
         pSource->process(aAppState, pSource);