Send key up events for the mouse wheel

Previous versions of SDL would send SDL_MOUSEBUTTONUP events for the mouse wheel immediately following the corresponding SDL_MOUSEBUTTONDOWN event

code/sdl/sdl_input.c

@@ -807,9 +807,15 @@ static void IN_ProcessEvents( void )
 
 			case SDL_MOUSEWHEEL:
 				if( e.wheel.y > 0 )
+				{
 					Com_QueueEvent( 0, SE_KEY, K_MWHEELUP, qtrue, 0, NULL );
+					Com_QueueEvent( 0, SE_KEY, K_MWHEELUP, qfalse, 0, NULL );
+				}
 				else
+				{
 					Com_QueueEvent( 0, SE_KEY, K_MWHEELDOWN, qtrue, 0, NULL );
+					Com_QueueEvent( 0, SE_KEY, K_MWHEELDOWN, qfalse, 0, NULL );
+				}
 				break;
 
 			case SDL_QUIT: