tree-optimization/102448 - clear copied alignment info from vect

tree-optimization/102448 - clear copied alignment info from vect

This fixes the previous change which removed setting alignment info
from the vectorizers idea of how a pointer is being used but left
in place the copied info from DR_PTR_INFO without realizing that this
is in fact _not_ the alignment of the access but the alignment of
a base pointer contained in it.

The following makes sure to not use that info.

2021-09-23  Richard Biener  <rguenther@suse.de>

	PR tree-optimization/102448
	* tree-vect-data-refs.c (vect_duplicate_ssa_name_ptr_info):
	Clear alignment info copied from DR_PTR_INFO.