MRE's for lts-saucy

[Maarten Lankhorst]

Hey,

I would like to request a MRE for getting the saucy libdrm copied to precise, quantal, raring.
Something similar has been done before, for getting the raring libdrm in quantal and precise[1].
libdrm cannot be renamed because it's an integral part of the system. Plymouth may fail
with older libdrm's, because it will not know about the newer pci-ids.

Similarly, I want to copy pixman from raring to quantal and precise. This package is used as
the base rendering library for cairo and xorg. The xorg-server headers depend on pixman for
some definitions, so I think upgrading pixman is preferred to renaming. Renaming will run into
all sorts of issues, again because packages cannot depend on versioned depends when the
package is renamed. The xserver in quantal has an identical abi to the one in raring, so copying
it should be harmless, but might in the worst case cause it to expose some cairo bugs that have
been in raring. The effects on precise I'm less certain about, I haven't noticed any issues when
testing against precise cairo, and upstream is conservative about updating pixman.

Last, I want to request a MRE for libxi and x11proto-input in precise. The upstream pointer barriers
have been merged, and I need to update libxi with a newer upstream version to get those pointer
barriers. I've written a patch to allow runtime detection in unity/unity-2d, so it can use the new or
old pointer barrier methods when it connects to the server and requests the xfixes/xi2 version.

[1] https://bugs.launchpad.net/ubuntu/+source/libdrm/+bug/1171340