Add in some conditional compilation in order to silence an unused variable warning.

llvm-svn: 180700
diff --git a/llvm/lib/Transforms/ObjCARC/ObjCARCOpts.cpp b/llvm/lib/Transforms/ObjCARC/ObjCARCOpts.cpp
index d95c9e8..e3d51d5 100644
--- a/llvm/lib/Transforms/ObjCARC/ObjCARCOpts.cpp
+++ b/llvm/lib/Transforms/ObjCARC/ObjCARCOpts.cpp
@@ -307,10 +307,12 @@
           "Number of retains before optimization.");
 STATISTIC(NumReleasesBeforeOpt,
           "Number of releases before optimization.");
+#ifndef NDEBUG
 STATISTIC(NumRetainsAfterOpt,
           "Number of retains after optimization.");
 STATISTIC(NumReleasesAfterOpt,
           "Number of releases after optimization.");
+#endif
 
 namespace {
   /// \enum Sequence