testsuite: Add testcase for recently fixed PR [PR101159]

testsuite: Add testcase for recently fixed PR [PR101159]

On Tue, Jun 22, 2021 at 11:00:51AM +0200, Richard Biener wrote:
> 2021-06-22  Richard Biener  <rguenther@suse.de>
>
>       PR tree-optimization/101159
>       * tree-vect-patterns.c (vect_recog_popcount_pattern): Add
>       missing NULL vectype check.

The following patch adds the testcase for it, IMHO it can't hurt and
from my experience testcases often trigger other bugs later on (rather
than the original bugs reappearing, though even that happens),
and also fixes a couple of typos in the new function.

2021-06-22  Jakub Jelinek  <jakub@redhat.com>

	PR tree-optimization/101159
	* tree-vect-patterns.c (vect_recog_popcount_pattern): Fix some
	comment typos.

	* gcc.c-torture/compile/pr101159.c: New test.