CGDebugInfo.cpp: Fix a warning. [-Wunused-variable]

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@173022 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/CodeGen/CGDebugInfo.cpp b/lib/CodeGen/CGDebugInfo.cpp
index 719bb69..ec88d87 100644
--- a/lib/CodeGen/CGDebugInfo.cpp
+++ b/lib/CodeGen/CGDebugInfo.cpp
@@ -1738,6 +1738,7 @@
     }
     
     assert(T != LastT && "Type unwrapping failed to unwrap!");
+    (void)LastT;
   } while (true);
 }