SelectionDAG switch lowering: use 'unsigned' to count destination popularity

SwitchInst::getNumCases() returns unsinged, so using uint64_t to count cases
seems unnecessary.

Also fix a missing CHECK in the test case.

llvm-svn: 224393
diff --git a/llvm/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp b/llvm/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp
index 3c0229f..81b824f 100644
--- a/llvm/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp
+++ b/llvm/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp
@@ -2712,8 +2712,8 @@
       !Cases.empty()) {
     // Replace an unreachable default destination with the most popular case
     // destination.
-    DenseMap<const BasicBlock *, uint64_t> Popularity;
-    uint64_t MaxPop = 0;
+    DenseMap<const BasicBlock *, unsigned> Popularity;
+    unsigned MaxPop = 0;
     const BasicBlock *MaxBB = nullptr;
     for (auto I : SI.cases()) {
       const BasicBlock *BB = I.getCaseSuccessor();