glx: Allow depth-30 pbuffers to work without a depth-30 pixmap format

The backing pixmap needs to be big enough to hold depth-30 rendering,
but the server doesn't necessarily have a depth-30 pixmap format. Just
round up to the 32bpp format you'd be using anyway.

Fixes: mesa/mesa#3527
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/6764>
1 file changed