DRI2 fixes and extensions

[Pauli]

I updated the last patch based Jesse's wish. i also added the review tags that
he gave to last two patches. I'm reposting the last patch ecause it has changed.

I also updated the branch holding the patches.

Sorry for the delay to handle the changes.

The following changes since commit a52efb096e166e325deb3d6b502671f339a4fa15:
  Keith Packard (1):
        Merge remote branch 'sthibaul/master-iopl'

are available in the git repository at:

  ssh://people/~suokko/xserver.git dri2_patches

Pauli Nieminen (5):
      DRI2: Avoid call to NULL pointer
      DRI2: Add error message when working around driver bug
      DRI2: Add ReuseBufferNotify hook
      DRI2: Expose API to set drawable swap limit.
      DRI2: Allow DDX to validate swap_limit changes

 hw/xfree86/dri2/dri2.c |   57 +++++++++++++++++++++++++++++++++++++++++++----
 hw/xfree86/dri2/dri2.h |   31 +++++++++++++++++++++++++-
 2 files changed, 82 insertions(+), 6 deletions(-)