[PATCH] Resending random patches for DRI2

[Pauli Nieminen]

Hi,

Following DRI2 patches are just random improvements that would help DRI2
driver implementation.

First 2 patches implement driver hooks that help implementing N-buffering
and shared page flip buffers.

Third patch is fix for NULL pointer dereference that was reported and fixed
here but not upstreamed yet.

Fourth patch is minor addition that makes DRI2 code report when it has to
workaround DDX bug. This same bug can still hit application that uses 
OML_sync_control.

Regards,
Pauli