Android: prevents rare crashes when app goes to background or ends.
Make sure the thread is actually paused, and context backep-up, before
SurfaceView is destroyed (eg surfaceDestroyed() actually returns).
Add a timeout when surfaceDestroyed() is called, and check 'backup_done' variable.
It prevents crashes like:
#00 pc 000000000000c0d0 /system/lib64/libutils.so (android::RefBase::incStrong(void const*) const+8)
#01 pc 000000000000c7f4 /vendor/lib64/egl/eglSubDriverAndroid.so (EglAndroidWindowSurface::UpdateBufferList(ANativeWindowBuffer*)+284)
#02 pc 000000000000c390 /vendor/lib64/egl/eglSubDriverAndroid.so (EglAndroidWindowSurface::DequeueBuffer()+240)
#03 pc 000000000000bb10 /vendor/lib64/egl/eglSubDriverAndroid.so (EglAndroidWindowSurface::GetBuffer(EglSubResource*, EglMemoryDesc*)+64)
#04 pc 000000000032732c /vendor/lib64/egl/libGLESv2_adreno.so (EglWindowSurface::UpdateResource(EsxContext*)+116)
#05 pc 0000000000326dd0 /vendor/lib64/egl/libGLESv2_adreno.so (EglWindowSurface::GetResource(EsxContext*, EsxResource**, EsxResource**, int)+56)
#06 pc 00000000002ae484 /vendor/lib64/egl/libGLESv2_adreno.so (EsxContext::AcquireBackBuffer(int)+364)
#07 pc 0000000000249680 /vendor/lib64/egl/libGLESv2_adreno.so (EsxContext::Clear(unsigned int, unsigned int, unsigned int, EsxClearValues*)+1800)
#08 pc 00000000002cb52c /vendor/lib64/egl/libGLESv2_adreno.so (EsxGlApiParamValidate::GlClear(EsxDispatch*, unsigned int)+132)
3 files changed
