Fix merges of non-zero vector stores

Fix merges of non-zero vector stores

Now actually stores the non-zero constant instead of 0.
I somehow forgot to include this part of r238108.

The test change was just an independent instruction order swap,
so just add another check line to satisfy CHECK-NEXT.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@239539 91177308-0d34-0410-b5e6-96231b3b80d8