fix stretch blit
i965: Fix miptree matching for multisampled, non-interleaved miptrees.

We haven't been executing this code before the meta-blit case, because
we've been flagging the miptree as validated at texstorage time, and never
having to revalidate.
meta: Add support for doing multisample resolves.
meta: Try to do blending of sRGB values in linear colorspace.

Blending of values would occur when doing GL_LINEAR filtering with
scaling, and in an upcoming commit when doing MSAA resolves.

!UPSTREAM: [citation needed]
meta: Save and restore a bunch of MSAA state.

We're disabling GL_MULTISAMPLE, so we didn't need to worry about a lot of
that state.  But to do MSAA to MSAA blits, we need to start handling more
state.

v2: Fix pasteo caught by Kenneth.
meta: Add support for doing MSAA to MSAA blits.
meta: Add support for integer blits.
i965: Drop blorp for glBlitFramebuffer() except for the stencil case.

I still need to do stencil for meta's blit path.
i965: Drop the blitter-based glBlitFramebuffer() path.

Now that meta can do single-copy blits even from renderbuffers and depth,
we don't need this any more.
Also emit VF_INSTANCING in the no-elements case.

I can't imagine why this would matter since there's no actual data being
pulled, but...for safety?

Not observed to help anything
stash - vp fixes?

doesn't seem to actually fix anything.

oh, this might only be relevant when I turn on the viewport extents test