tree-optimization/105219 - bogus max iters for vectorized epilogue

The following makes sure to take into account prologue peeling
when trying to narrow down the maximum number of iterations
computed for the vectorized epilogue.  A similar issue exists when
peeling for gaps.

2022-04-27  Richard Biener  <rguenther@suse.de>

	PR tree-optimization/105219
	* tree-vect-loop.cc (vect_transform_loop): Disable
	special code narrowing the vectorized epilogue max
	iterations when peeling for alignment or gaps was in effect.

	* gcc.dg/vect/pr105219.c: New testcase.