[43/46] Make free_stmt_vec_info take a stmt_vec_info

[43/46] Make free_stmt_vec_info take a stmt_vec_info

This patch makes free_stmt_vec_info take the stmt_vec_info that
it's supposed to free and makes it free only that stmt_vec_info.
Callers need to update the statement mapping where necessary
(but now there are only a couple of callers).

This in turns means that we can leave ~vec_info to do the actual
freeing, since there's no longer a need to do it before resetting
the gimple_uids.

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

gcc/
	* tree-vectorizer.h (free_stmt_vec_info): Take a stmt_vec_info
	rather than a gimple stmt.
	* tree-vect-stmts.c (free_stmt_vec_info): Likewise.  Don't free
	information for pattern statements when passed the original
	statement; instead wait to be passed the pattern statement itself.
	Don't call set_vinfo_for_stmt here.
	(free_stmt_vec_infos): Update call to free_stmt_vec_info.
	* tree-vect-loop.c (_loop_vec_info::~loop_vec_info): Don't free
	stmt_vec_infos here.
	* tree-vect-slp.c (_bb_vec_info::~bb_vec_info): Likewise.
	* tree-vectorizer.c (vec_info::remove_stmt): Nullify the statement's
	stmt_vec_infos entry.

From-SVN: r263158