This was used to make all ioctl handlers return -errno on linux and errno on
*BSD. Instead, just return -errno in shared code, and flip sign on return from
shared code to *BSD code.
Introduce tile members for future tiled buffer support.
Allow user-space to explicitly define a fence-class.
Remove the implicit fence-class mechanism.
64-bit wide buffer object flag member.
Eric Anholt
Dave Airlie
Thomas Hellstrom