xserver-xorg: update to 1.20.12

xserver-xorg: update to 1.20.12

Stable branch update:

b88ad0b34 (tag: xorg-server-1.20.12) xserver 1.20.12
8dea50223 Build xz tarballs instead of bzip2
b7adbac7d hw/dmx/config: Link directly with libdmxconfig.a
e49738f0c xfree86: Fix NULL pointer dereference crash
9a59631a4 glx: Fix use after free in MakeCurrent
1fc0ca6e6 xfree86: Fix out of array bound access to xf86Entities
a4210fe07 xfree86: Change displays array to pointers array to fix invalid pointer issues after table reallocation
22449f630 glamor: Avoid using GL_QUADS on V3D
d16f64031 modesetting: Fix possible_crtcs
f1e76731a modesetting: Update props for dynamically added outputs
7bf477711 xquartz: Ensure the mouse pointer is shown when switching to a native macOS alert or window
3ef6e7b76 xquartz: Fix appFlags build failure with macOS 10.15+ SDKs
2a83c840c glx: Set ContextTag for all contexts
394b6cc1c glx: don't create implicit GLXWindow if one already exists
0086535e7 modesetting: Remove few common functions from ms namespace
321964443 modesetting: remove unnecessary ms_covering_xf86_crtc dup of ms_covering_randr_crtc
52eb801d0 modesetting: Find crtc on slave outputs as fallback instead of returning primary crtc
c7a2da7b9 present: fix msc offset calculation in screen mode
31544e68e present: Use crtc's screen present operation for syncing
464cbee1c modesetting: Initialize present extension despite glamor is disabled
4e11bd390 modesetting: Disable reverse prime offload mode for displays running on evdi,udl
627252933 dix: Guard against non-existing PtrFeedbackPtr
d41b43345 xwayland: Add PtrFeedback to the touch device
23a53f0d5 glx: fixup symbol name for get_extensions function

Signed-off-by: Steve Sakoman <steve@sakoman.com>