Consider parm types equivalence for operator rewrite tiebreaker.

Consider parm types equivalence for operator rewrite tiebreaker.

The C++ committee continues to discuss how best to avoid breaking existing
code with the new rules for reversed operators.  A recent suggestion was to
base the tie-breaker on the parameter types of the candidates, which made a
lot of sense to me, so this patch implements that.

This patch also mentions that a candidate was reversed or rewritten when
printing the list of candidates, and warns about a comparison that becomes
recursive under the new rules.  There is no flag for this warning; people
can silence it by swapping the operands.

	* call.c (same_fn_or_template): Change to cand_parms_match.
	(joust): Adjust.
	(print_z_candidate): Mark rewritten/reversed candidates.
	(build_new_op_1): Warn about recursive call with reversed arguments.

From-SVN: r278465