x11/xdm: Update to 1.1.12

Update x11/xdm to 1.1.12.
This is a big release, incorporating over 7 years worth of changes.

Changelog:
https://lists.x.org/archives/xorg-announce/2019-March/002959.html

Obtained from: FreeBSD Graphics Team development repo

		https://github.com/FreeBSDDesktop/freebsd-ports/tree/feature/xorglibs

MFH: 2019Q3
Seucrity: CVE-2013-2179
Sponsored by: B3 Init