Don't install SDL default signal handler for Atlas

If we catch the signal we'd have to communicate that we terminated by
signal, which might depend on shell. There is also the issue of various
dialogs blocking regular quit which we don't want, so that would need
extra work as well.

As such just let the SIGINT/SIGTERM do there default action and forgo
cleanup and let the OS handle it.

Fixes: #198
Signed-off-by: Ralph Sennhauser <ralph.sennhauser@gmail.com>

source/tools/atlas/GameInterface/Handlers/GraphicsSetupHandlers.cpp

@@ -109,6 +109,7 @@ MESSAGEHANDLER(InitAppWindow)
 
 MESSAGEHANDLER(InitSDL)
 {
+	SDL_SetHint(SDL_HINT_NO_SIGNAL_HANDLERS, "1");
 	// When using GLX (Linux), SDL has to load the GL library to find
 	// glXGetProcAddressARB before it can load any extensions.
 	// When running in Atlas, we skip the SDL video initialisation code