Remove dead part of bool pattern recognition

Remove dead part of bool pattern recognition

Given we no longer want vcond[u]{,_eq} and VEC_COND_EXPR or COND_EXPR
with embedded GENERIC comparisons the whole check_bool_pattern
and adjust_bool_stmts machinery is dead.  It is effectively dead
after r15-4713-g0942bb85fc5573 and the following patch removes it.

	* tree-vect-patterns.cc (check_bool_pattern): Remove.
	(adjust_bool_pattern_cast): Likewise.
	(adjust_bool_pattern): Likewise.
	(sort_after_uid): Likewise.
	(adjust_bool_stmts): Likewise.
	(vect_recog_bool_pattern): Remove calls to check_bool_pattern
	and fold as if it returns false.