middle-end/101291 - set loop copy of versioned loop

middle-end/101291 - set loop copy of versioned loop

This fixes the vectorizer loop versioning code failing to clear
niter related info on the scalar loop as it assumed get_loop_copy
would work even for the outermost loop.  The patch makes that
assumption hold by adjusting the loop versioning code.

2021-07-05  Richard Biener  <rguenther@suse.de>

	PR middle-end/101291
	* cfgloopmanip.c (loop_version): Set the loop copy of the
	versioned loop to the new loop.