norfanin
Some of the tests keep using the pointers of a destroyed SDL_Window when the common event handling handled the close event. The event handler itself does not NULL the pointer after the destruction.
The attached patch adds a loop in the handler that will assign NULL to the destroyed window. It also adds checks to some of the tests so they skip those windows by checking for NULL.
If ac_x_libraries is empty it means that the library's found in the default path,
so we skip adding it to the XLIB variable as it screws up the search path.
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.
