1st pass at supporting the altix platform for Xorg.

[Shrijeet Mukherjee]

Hello, 

I have added a bug and attached a patch for supporting the Altix
(itanium-linux) platform under Xorg.

The bug (and patch) is at
https://bugs.freedesktop.org/show_bug.cgi?id=2373

The highlights of the change, for which I need feedback about are ..

1. Turning on a DomainSupport for the IA64 platform.
2. Using a legacyIO api that is available only from linux-2.6.11 onwards 
(failure      to find these interfaces makes the Xserver revert to the current
code paths)
3. Creating a pciBusAddrToHostAddr function for allowing drivers to examine the
/proc/bus/pci interface to convert bus addrs to host addrs to catch the case of
machines that do not have all IO mapped in the low 4GB. (again if all the IO is
 in the low memory things should just work right)

Thanx