drisw: Port the MIT-SHM check to XCB
The old version isn't thread-safe, and xlib makes it unreasonably difficult to write thread-safely.
Fixes: #3398 (closed)
Due to an influx of spam, we have had to impose restrictions on new accounts. Please see this wiki page for instructions on how to get full permissions. Sorry for the inconvenience.
The old version isn't thread-safe, and xlib makes it unreasonably difficult to write thread-safely.
Fixes: #3398 (closed)