middle-end/104402 - split out _Complex compares from COND_EXPRs

middle-end/104402 - split out _Complex compares from COND_EXPRs

This makes sure we always have a _Complex compare split to a
different stmt for the compare operand in a COND_EXPR on GIMPLE.
Complex lowering doesn't handle this and the change is something
we want for all kind of compares at some point.

2022-02-07  Richard Biener  <rguenther@suse.de>

	PR middle-end/104402
	* gimple-expr.cc (is_gimple_condexpr): _Complex typed
	compares are not valid.
	* tree-cfg.cc (verify_gimple_assign_ternary): For COND_EXPR
	check is_gimple_condexpr.

	* gcc.dg/torture/pr104402.c: New testcase.