[PATCH xserver 0/2] Simplify GC ops interface

[Keith Packard]

Removing miTranslate from the GC and support for CoordModePrevious in
points/lines/polygons makes drivers simpler and fixes bugs in
CoordModePrevious support for dots in damage and rootless.

My eventual goal is to make the primitive coordinates parameters
const, which will eliminate the need to save/restore them in Xinerama
and also allow for some future damage-related improvements.

(just to be clear, this is post-1.19 work)