updae source to 2.0.9 source

Edward Rudd

2019-04-09 9cd2e9ec8fc0127393dfce9c0359d500c8c238be

 source/src/video/cocoa/SDL_cocoamousetap.m

@@ -236,6 +236,13 @@
{
    SDL_MouseEventTapData *tapdata = (SDL_MouseEventTapData*)driverdata->tapdata;
    int status;

    if (tapdata == NULL) {
        /* event tap was already cleaned up (possibly due to CGEventTapCreate
         * returning null.)
         */
        return;
    }

    /* Ensure that the runloop has been started first.
     * TODO: Move this to InitMouseEventTap, check for error conditions that can