BBVectorize: Fix a small bug introduced in r167042.

We need to make sure that we take the correct load/store alignment
when the inputs are flipped.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@167044 91177308-0d34-0410-b5e6-96231b3b80d8

lib/Transforms/Vectorize/BBVectorize.cpp

@@ -2472,7 +2472,6 @@ namespace {
       Instruction *L = I, *H = J;
       if (FlipMemInputs)
         std::swap(H, L);
-      FlipMemInputs = false;
 
       unsigned NumOperands = I->getNumOperands();
       SmallVector<Value *, 3> ReplacedOperands(NumOperands);