Silence some release build warnings.

llvm-svn: 91234
diff --git a/clang/lib/Sema/SemaInit.cpp b/clang/lib/Sema/SemaInit.cpp
index db56438..e8794b1 100644
--- a/clang/lib/Sema/SemaInit.cpp
+++ b/clang/lib/Sema/SemaInit.cpp
@@ -2115,6 +2115,7 @@
   assert(!S.CompareReferenceRelationship(Initializer->getLocStart(), 
                                          T1, T2, DerivedToBase) &&
          "Must have incompatible references when binding via conversion");
+  (void)DerivedToBase;
 
   // Build the candidate set directly in the initialization sequence
   // structure, so that it will persist if we fail.