[PATCH] [followup to PR59569] new vect tests for store with negative step

[Bingfeng Mei]

Hi, 
Here are two vectorization tests for store with negative step. This is 
follow-up to PR59569 fix, which contains two tests for ICE. These tests are for 
vectorization tests and executable. OK to commit? 

Thanks,
Bingfeng

patch_vect_tests
Description: patch_vect_tests