Add minimize command (#4531)

code/sdl/sdl_glimp.c

@@ -99,6 +99,19 @@ void GLimp_Shutdown( void )
 	Com_Memset( &glState, 0, sizeof( glState ) );
 }
 
+/*
+===============
+GLimp_Minimize
+
+Minimize the game so that user is back at the desktop
+===============
+*/
+void GLimp_Minimize(void)
+{
+	SDL_WM_IconifyWindow();
+}
+
+
 /*
 ===============
 GLimp_LogComment