[01/11] Schedule SLP earlier

[01/11] Schedule SLP earlier

vect_transform_loop used to call vect_schedule_slp lazily when it
came across the first SLP statement, but it seems easier to do it
before the main loop.

2018-07-30  Richard Sandiford  <richard.sandiford@arm.com>

gcc/
	* tree-vect-loop.c (vect_transform_loop_stmt): Remove slp_scheduled
	argument.
	(vect_transform_loop): Update calls accordingly.  Schedule SLP
	instances before the main loop, if any exist.

From-SVN: r263214