tree-optimization/122301 - fix ICE and improve vectorization of min/max reduction

tree-optimization/122301 - fix ICE and improve vectorization of min/max reduction

The following fixes another issue with updating of reduc_idx in pattern
sequences.  But the testcase also shows the pattern in question is
harmful for vectorization since a reduction path may not contain
promotions/demotions.  So the already existing but ineffective check
to guard the pattern is fixed.

	PR tree-optimization/122301
	* tree-vect-patterns.cc (vect_recog_over_widening_pattern):
	Fix reduction guard.
	(vect_mark_pattern_stmts): Fix reduction def check.

	* gcc.dg/vect/vect-pr122301.c: New testcase.