[PATCH xserver/dri2] Improvements to DRI2 2.2 protocol bits.

[Mario Kleiner]

The following series of 3 patches contains some bug fixes and adds some
missing functionality to the new DRI2 2.2 protocol requests for
implementation of the SGI_swap_interval and OML_sync_control GLX
extensions.

Jesse Barnes already had a positive look at these patches, but i couldn't test
any of the patches, not even if they compile, due to lack of suitable hardware.

Could somebody please test these and apply them if appropriate?

Thanks,
mario