This patch removes the stmt_vec_info wrapper class added near the
beginning of the series and turns stmt_vec_info back into a typedef.

2018-07-31  Richard Sandiford  <richard.sandiford@arm.com>

gcc/
	* tree-vectorizer.h (stmt_vec_info): Turn back into a typedef.
	(NULL_STMT_VEC_INFO): Delete.
	(stmt_vec_info::operator*): Likewise.
	(stmt_vec_info::operator gimple *): Likewise.
	* tree-vect-loop.c (vectorizable_reduction): Use NULL instead
	of NULL_STMT_VEC_INFO.
	* tree-vect-patterns.c (vect_init_pattern_stmt): Likewise.
	(vect_reassociating_reduction_p): Likewise.
	* tree-vect-stmts.c (vect_build_gather_load_calls): Likewise.
	(vectorizable_store): Likewise.
	* tree-vectorizer.c (vec_info::set_vinfo_for_stmt): Likewise.
	(vec_info::free_stmt_vec_infos): Likewise.

From-SVN: r263161