[Intel-gfx] metaops for review

[Eric Anholt]

Here are a pair of patches I've been working on for the metaops work.
They're not quite ready at this point as they regress some oglconform cases,
and I'm hoping someone with an eye for detail can see what I'm doing wrong.

glBitmap is about half to a quarter the speed of the blit path, but works
in the presence of depth test, stencil test, zooming, and other things.  It
should speed up a bunch of oglconform testcases (such as spop.c), and Blender
as well.  Once the bugs are worked out, I'll have the general version called
only if the faster blit path fails.

glDrawPixels(GL_DEPTH_COMPONENT) is just for oglconform as far as I know.
However, there are a bunch of tests that are really hurt by it not being
accelerated, such as blend-separate.c.