Fixes #2022, do not resume on Android when surfaceChanged

If the app is in landscape mode and the user presses the power button, a pause
is followed immediately by a surfaceChanged event because the lock screen
is shown in portrait mode. This triggers a "false" resume.
So, we just pause and resume following the onWindowFocusChanged events.

Also, wait for SDL_APP_WILLENTERBACKGROUND and SDL_APP_DIDENTERBACKGROUND before
blocking the event pump.

VisualC/clean.sh

@@ -0,0 +1,5 @@
+find . -type d -name 'Debug' -exec rm -rv {} \;
+find . -type d -name 'Release' -exec rm -rv {} \;
+find . -type f -name '*.user' -exec rm -v {} \;
+find . -type f -name '*.ncb' -exec rm -v {} \;
+find . -type f -name '*.suo' -exec rm -v {} \;