Fix immersive full screen mode doesn't recover

Immersive Fullscreen mode doesn´t recover after changing the volume on the device.
Refer https://github.com/libgdx/libgdx/issues/1468 to fix this issue.

BUG=XWALK-2424
Merge pull request #155 from fujunwei/full-screen

Fix immersive full screen mode doesn't recover