Implement some of fold_binary_op_with_conditional_arg in match.pd

Implement some of fold_binary_op_with_conditional_arg in match.pd

The following allows (c != 0 ? 0 : 100) != 0 to be simplified as
c != 0 as fold_binary_op_with_conditional_arg would have done
via forwprop and GENERIC folding.  Likewise it allows to combine
(a != 0) != 0 directly via match.pd instead of only via
forwprop and again fold_binary_op_with_conditional_arg.

The patterns do not fully implement all cases of
fold_binary_op_with_conditional_arg, some aspects like
"any of the operands simplify" cannot currently be expressed.

2022-05-11  Richard Biener  <rguenther@suse.de>

	* generic-match-head.cc: Include tree-eh.h.
	* match.pd ((cond ...) cmp X): New simplification inspired
	by fold_binary_op_with_conditional_arg.
	(eq/ne (cmp ...) true/false): Likewise.

	* gcc.dg/tree-ssa/pr61839_1.c: Adjust.
	* gcc.dg/tree-ssa/vrp24.c: Likewise.