add support for the boneheaded method of receiving input events that is used by NativeActivity apps

currently, our "not-actually-a-queue" implementation is quite ugly,
hopefully it might be possible to make it look somewhat sane while
not needing to make it as much of a queue as it is on android

src/api-impl-jni/util.h

@@ -57,6 +57,10 @@ struct handle_cache {
 		jclass class;
 		jmethodID onPeriodicNotification;
 	} audio_track_periodic_listener;
+	struct {
+		jclass class;
+		jmethodID onInputQueueCreated;
+	} input_queue_callback;
 	struct {
 		jclass class;
 		jmethodID setLayoutParams;