This fixes artifacts being displayed to screen during start-up of the game 'Draw & Guess'. The artifacts are the result of random data in the memory allocated by `malloc` making their way to an `XPutImage` call within `x11drv_surface_flush`. I'm not 100% sure if this is the correct fix. It could be that `x11drv_surface_flush` should have a means to detect when the image data has not been initialised and then skip the `XPutImage` call. It looks like the current allocation was introduced in 2012 as a part of [70a511739eb7 ](https://gitlab.winehq.org/wine/wine/-/commit/70a511739eb7502340e800bbab0fa08...). But things have changed enough since then that it might now make sense to zero this allocation. Notably, there is a second allocation in that commit that is zeroed. -- https://gitlab.winehq.org/wine/wine/-/merge_requests/10356