Workaround resume/pause deadlock in Android by killing

https://github.com/libgdx/libgdx/issues/904

Repro steps:
1. Open libgdx app.
2. Open Android Recent Apps.
3. Double-tap Recent Apps with ~500ms between taps.
4. Tap Recent Apps once to bring libgdx app back -- if it comes back with no ANR, repeat steps 2-3.

As an interim bandaid we are killing the app if pause takes longer than 4 seconds (ANR is 5 seconds).

With this patch, the app closes during pause instead of ANRing.