community/xorg-server: allow rootless X server

This patch fixes the suid flag in /usr/libexec/Xorg.wrap (instead of /usr/bin/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.