Maintain LC SSA when doing SVE vectorization

Maintain LC SSA when doing SVE vectorization

The final loop IV use after the loop has that not in LC SSA
(and inserts not simplified _2 = _3 - 0 stmts).  In particular
since it splits the exit edge when there's a virtual PHI in the
destination it breaks virtual LC SSA form (but likely also
non-virtual).

The following properly inserts LC PHIs instead.

2022-07-04  Richard Biener  <rguenther@suse.de>

	* tree-vect-loop-manip.cc (vect_set_loop_condition_normal):
	Maintain LC SSA.