i965: Fix repeated usage of rectangle texture coordinate scaling.

i965: Fix repeated usage of rectangle texture coordinate scaling.

Previously, we set up new entries in the params[] array on every access
of a rectangle texture.  Unfortunately, we only reserve space for
(2 * MaxTextureImageUnits) extra entries, so programs which accessed
rectangle textures more times than that would write off the end of the
array and likely crash.

We don't really have a decent mapping between the index returned by
_mesa_add_state_reference and our index into the params array, so we
have to manually search for it.

Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=78691
Signed-off-by: Kenneth Graunke <kenneth@whitecape.org>
Reviewed-by: Ian Romanick <ian.d.romanick@intel.com>
Reviewed-by: Eric Anholt <eric@anholt.net>
Cc: mesa-stable@lists.freedesktop.org