Fixed glitch with GLSurfaceView_SDL when setting targetSdkVersion higher than Gingerbread

This is modifying the original code from SDL implementing android when
wanting to target something higher than Gingerbread by replacing
onStop event with onUserLeaveHint.

Starting from Honeycomb, the activity lifecycle runs "onStop" when
turning off the device and causes the thread to freeze
(wait forever). Only the event onUserLeaveHint runs when putting the
app into the background and does not run when user turns off the
device. Before Honeycomb, the lifecycle would only run "onStop" when
bringing the app to background.

For replacing the two events, we are now able to raise targetSdkVersion
above Gingerbread without any freezing.
Removed the redundent call for onResume and onPause