Silence an unused variable warning.

llvm-svn: 101438
diff --git a/llvm/lib/VMCore/Pass.cpp b/llvm/lib/VMCore/Pass.cpp
index 987712a..a60877d 100644
--- a/llvm/lib/VMCore/Pass.cpp
+++ b/llvm/lib/VMCore/Pass.cpp
@@ -331,7 +331,7 @@
     PassRegistrarObj = 0;
   }
 }
-ManagedCleanup<&cleanupPassRegistrar> registrarCleanup;
+ManagedCleanup<&cleanupPassRegistrar> registrarCleanup ATTRIBUTE_USED;
 
 }