cris.md: Reinstate add/sub with extend

cris.md: Reinstate add/sub with extend

When cleaning out the multitude of patterns with unknown
coverage, this one went the way of the bathwater.  It's use is
barely common enough to mark when diffing libgcc, and has a
minimal impact on performance-testsuites.  Anyway, reinstated
with a couple of test-cases.  It's suboptimal of gcc-core not to
make use of the SImode pattern when performing HImode; see the
FIXME (which is actually also reinstated).

This version uses match_operator, for continuity but will be
replaced with a version making use of iterators (like it does
for the mode).

gcc:
	* config/cris/cris.md ("*extopqihi", "*extop<mode>si<setnz>_swap")
	("*extop<mode>si<setnz>", "*addxqihi_swap"): Reinstate.

gcc/testsuite:
	* gcc.target/cris/pr93372-36.c, gcc.target/cris/pr93372-37.c,
	gcc.target/cris/pr93372-38.c: New tests.