Merge: android/audio: fix multiple music playing when pausing app

Asked by @privat because friendz's app played multiple musics when pausing/resuming the app

Pull-Request: #1721
Reviewed-by: Jean Privat <jean@pryen.org>
Reviewed-by: Alexis Laferrière <alexis.laf@xymus.net>
Reviewed-by: Lucas Bajolet <r4pass@hotmail.com>