Build xorg-server with autotools

This merge request builds xorg-server with autotools instead of meson, which required adding the include path to the custom %{libdir}/GL/degault/include manually as it seems not to be automatically picked up by the pkgconfig file.

The change to autotools is currently necessary to build on arm, as the meson build is not working there (it appears to not choose the correct int10 backend, and then fails to include asm/vm86.h which doesnt exist on arm).