powerpc/165585: x11-servers/xorg-server: Both Xorg and Xorg-server port installs break when dri is being built

[Mark Linimon]

Please take a look at a PR that I have recently submitted, ports/169874.

In it I am trying to look at dri/libGL/libdrm on all the tier-2 archs,
not just powerpc.

I have built on patches initially developed and tested by marius at .

See what you think about these two ideas:

 - I believe the patch in 169874 for libdrm is more general than the one
   in this PR.  Do you agree?

 - There is a patch in that PR for src/mesa/drivers/dri/radeon/radeon_span.c.
   With that, is your patch for libGL still necessary?

Thanks.

mcl