tree-optimization/100359 - restore unroll at -O3

tree-optimization/100359 - restore unroll at -O3

This fixes a mistake done with r8-5008 when introducing
allow_peel to the unroll code.  The intent was to allow
peeling that doesn't grow code but the result was that
with -O3 and UL_ALL this wasn't done.  The following
instantiates the desired effect by adjusting ul to UL_NO_GROWTH
if peeling is not allowed.

2022-01-05  Richard Biener  <rguenther@suse.de>

	PR tree-optimization/100359
	* tree-ssa-loop-ivcanon.c (try_unroll_loop_completely):
	Allow non-growing peeling with !allow_peel and UL_ALL.

	* gcc.dg/tree-ssa/pr100359.c: New testcase.