Don't copy a potentially-uninitialized variable.

Based on review discussion of r158638 with Chandler Carruth, Tobias von Koch, and Duncan Sands and a -Wmaybe-uninitialized warning from GCC.

llvm-svn: 158685

llvm/include/llvm/ADT/DenseMap.h

@@ -490,7 +490,7 @@ private:
 
   template <typename LookupKeyT>
   bool LookupBucketFor(const LookupKeyT &Val, BucketT *&FoundBucket) {
-    const BucketT *ConstFoundBucket = FoundBucket;
+    const BucketT *ConstFoundBucket;
     bool Result = const_cast<const DenseMapBase *>(this)
       ->LookupBucketFor(Val, ConstFoundBucket);
     FoundBucket = const_cast<BucketT *>(ConstFoundBucket);