Enforce continuous rendering while pausing Android backends
Add volatile keyword so that pause is thread safe

on enforceContinuousRenderingOnPause that is write/read by two threads
Rename enforceContinuousRendering variable in AndroidGraphics
Merge pull request #2472 from avianey/master

Enforce continuous rendering while pausing Android backends
Merge branch 'master' of https://github.com/libgdx/libgdx into PR2431
Update CHANGES for KTX/ZKTX support