temp/xorg-server: fork previous 1.20.11 version

xorg-server has stopped working since 1.20.12 version.

Seems that this upstream issue aports#11347 is the root cause.
For now, I'd like to workaround it until some solution is addressed.

Related: #1150 (closed) , #1236 (closed)

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Steps to reproduce:
pmbootstrap init -> Select your device -> Select any UI that goes with X -> Try to boot into UI.

Also (if trying from scratch):
pmbootstrap init -> Select your device -> Select none
Then, flash, boot your device and type (let's try with xfce4, for example):
$ sudo setup-xorg-base xfce4 xfce4-screensaver dbus-x11 lightdm lightdm-gtk-greeter.
$ sudo service lightdm start

Same result. It seems to run but nothing is shown at all.