app/build.gradle: update NDK stuff for gradle
app/build.gradle: update NDK stuff for gradle

This enables stuff to work with Android Studio 2.x it seems,
although my laptop works fine without these things :P

Requires overriding dependencies_prefix

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