ir_to_mesa: Don't assertion fail on remaining GLSL 1.30 ops.

ir_to_mesa: Don't assertion fail on remaining GLSL 1.30 ops.

For hardware drivers, we only have ir_to_mesa called for the purposes
of potential swrast fallbacks (basically never on a 1.30 driver),
which we don't really care about.  This will allow 1.30 to be
implemented without rewriting swrast for it.

Reviewed-by: Chad Versace <chad@chad-versace.us>
Reviewed-by: Kenneth Graunke <kenneth@whitecape.org>