xorg-server: Add patches to fix security issues

Patch xorg-server (and sub ports) to fix recently discovered security isses:
CVE-2020-14360 and CVE-2020-25712.

These issues can lead to privileges elevations for authorized clients
on systems where the X server is running privileged.

Tested by: adridg, tcberner, mikael
MFH: 2020Q4
Security: 76c8b690-340b-11eb-a2b7-54e1ad3d6335