Fix non-deterministic behavior.

We use CSEBlocks to initialize a worklist:

SmallVector<BasicBlock *, 8> CSEWorkList(CSEBlocks.begin(), CSEBlocks.end());

so it must have a deterministic order.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@196520 91177308-0d34-0410-b5e6-96231b3b80d8

lib/Transforms/Vectorize/SLPVectorizer.cpp

@@ -521,7 +521,7 @@ private:
   /// Holds all of the instructions that we gathered.
   SetVector<Instruction *> GatherSeq;
   /// A list of blocks that we are going to CSE.
-  SmallSet<BasicBlock *, 8> CSEBlocks;
+  SetVector<BasicBlock *> CSEBlocks;
 
   /// Numbers instructions in different blocks.
   DenseMap<BasicBlock *, BlockNumbering> BlocksNumbers;