x11-servers/xorg-server: Fix CVE-2020-14347

Add upstream patch to fix CVE-2020-14347, Pixel Data Uninitialized Memory
Information Disclosure.
Announcement:
https://lists.x.org/archives/xorg-announce/2020-July/003051.html

PR: 248410 (based on)
Submitted by: VVD
MFH: 2020Q3 (implicit, security update)
Security: 3c7ba82a-d3fb-11ea-9aba-0c9d925bbbc0