xorg-server 1.18 ready for testing on x86 and shark

hi folks.


i've gotten native xorg server updated to 1.18.4 and working for me
on i386, amd64 and shark.  more testing is needed.

to test, simply pass -V HAVE_XORG_SERVER_VER=118 to build.sh or set
it in mk.conf.

if you'd like to test, i recommend having a completely clean obj
and destdir for it (one of the failure modes is kdump not building.)
i also welcome help porting to other platforms, or updating drivers
(many older drivers are disabled with the newer server mostly due to
needing to be updated for modern xorg-server APIs.)

this also enables the xf86-video-amdgpu driver that supports modern
amd gpus.

as always, please send-pr to send me email about issues.


.mrg.