When I originally implemented the ARB_copy_image extension, the fast-path
was written in meta using texture views.  This path only worked if both
images were uncompressed color images.  All of the other cases fell back to
the blitter or, in the worst case, mapping and memcpy on the CPU.  Now that
we have the blorp path, it handles all copies ever and the old meta,
blitter, and CPU paths are only used on gen5 and below.  The primary reason
why we needed the meta path (apart from having a slow blitter on later
hardware) was to handle multisampling which gen5 and earlier don't support
anyway.  Since the blitter is reasonably fast on gen5, we can just delete
the meta path and get rid of all that terrible code.

If we decide that we're ok with just disabling ARB_copy_image on gen5 and
earlier (I personally am), then we could get rid of another 300 lines or so
of semi-hairy code.

Reviewed-by: Anuj Phogat <anuj.phogat@gmail.com>