Daniel Ribeiro Maciel
CMake is not adding src/core/linux/*.c to the build, linking to SDL results in errors:
(...)/libSDL2-2.0.so.1.0.1: undefined reference to `SDL_UDEV_AddCallback'
(...)/libSDL2-2.0.so.1.0.1: undefined reference to `SDL_UDEV_Poll'
(...)/libSDL2-2.0.so.1.0.1: undefined reference to `SDL_UDEV_Init'
(...)/libSDL2-2.0.so.1.0.1: undefined reference to `SDL_UDEV_Quit'
(...)/libSDL2-2.0.so.1.0.1: undefined reference to `SDL_UDEV_DelCallback'
(...)/libSDL2-2.0.so.1.0.1: undefined reference to `SDL_UDEV_Scan'
collect2: error: ld returned 1 exit status
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.
