Unhappy Xorg upgrade

[Bruce Simpson]

I can confirm that with 7-STABLE as of this writing, the USB problems 
with amd64 and Xorg appear to be fixed.

The key requirements are a 7-STABLE tree from *now*, a fresh 
buildworld+buildkernel, and a forced rebuild of libpciaccess to pick up 
PCIOCGETBAR. I can now run both scanpci and Xorg without seeing the loss 
of USB functionality from before.

Thanks to jhb@ and rnoland@ for backporting the fixes!

cheers,
BMS