- put SDL_Quit into the atexit queue instead of atterm

System exit procedures should not go in there.

src/posix/sdl/i_main.cpp

@@ -179,7 +179,7 @@ int main (int argc, char **argv)
 		fprintf (stderr, "Could not initialize SDL:\n%s\n", SDL_GetError());
 		return -1;
 	}
-	atterm (SDL_Quit);
+	atexit (SDL_Quit);	// This one should NOT be in the engine's list of exit handlers!
 
 	printf("\n");