[NewGVN] Fix a bug that made the store verifier less effective.

We weren't actually checking for duplicated stores, as the condition
was always actually false. This was found by Coverity, and I have
no clue how to trigger this in real-world code (although I
 tried for a bit).

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@305867 91177308-0d34-0410-b5e6-96231b3b80d8
1 file changed