Revert "i965: Don't _swrast_BlitFramebuffer when doing CopyTexSubImage."

Revert "i965: Don't _swrast_BlitFramebuffer when doing CopyTexSubImage."

This reverts commit bd44ac8b5ca08016bb064b37edaec95eccfdbcd5.

Fixes:
Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=78842
Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=78843

Re-breaks:
Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=77705
but that will be fixed properly in a few commits.

Reviewed-by: Ian Romanick <ian.d.romanick@intel.com>
Reviewed-by: Chris Forbes <chrisf@ijw.co.nz>
Cc: "10.2" <mesa-stable@lists.freedesktop.org>