community/xorg-server: allow rootless X server

This patch fixes the suid flag in /usr/libexec/Xorg.wrap (instead of
/usr/libexec/Xorg) and installs the related wrapper script in
/usr/bin/X, so rootless X server becomes possible. This is the same
approach used by Debian, Void Linux and many other distros.

It also fixes a wrong SYSCONFDIR pointing to /etc/X11 instead of /etc,
making X server programs look at /etc/X11/X11 for most configuration
files.
7 jobs for !16022 with xorg-xserver in 2 minutes and 38 seconds
detached
Status Job ID Name Coverage
  Lint
passed #279269
docker-alpine x86_64
lint

00:00:19

 
  Build
passed #279274
docker-alpine ci-build aarch64
build-aarch64

00:01:44

passed #279275
docker-alpine ci-build armv7
build-armv7

00:02:07

passed #279273
docker-alpine ci-build ppc64le
build-ppc64le

00:02:17

passed #279272
docker-alpine ci-build s390x
build-s390x

00:02:09

passed #279271
docker-alpine ci-build x86
build-x86

00:01:11

passed #279270
docker-alpine ci-build x86_64
build-x86_64

00:01:22