Fix a bunch of unused variable warnings when doing a release
build with gcc-4.6.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@142350 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp b/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp
index 309b68b..24bd2cd 100644
--- a/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp
+++ b/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp
@@ -2474,7 +2474,7 @@
   size_t numCmps = Clusterify(Cases, SI);
   DEBUG(dbgs() << "Clusterify finished. Total clusters: " << Cases.size()
                << ". Total compares: " << numCmps << '\n');
-  numCmps = 0;
+  (void)numCmps;
 
   // Get the Value to be switched on and default basic blocks, which will be
   // inserted into CaseBlock records, representing basic blocks in the binary