MPVActivity: fix crash when using gestures and time-pos is not available
MPVActivity: fix crash when using gestures and time-pos is not available

jeeb/mpv-android,jeeb/mpv-android,mpv-android/mpv-android,mpv-android/mpv-android,mpv-android/mpv-android,jeeb/mpv-android,jeeb/mpv-android,mpv-android/mpv-android,jeeb/mpv-android,mpv-android/mpv-android