Fix memory leak of IdentifierIterator object.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@118371 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Sema/SemaLookup.cpp b/lib/Sema/SemaLookup.cpp
index f0c21f4..65e8659 100644
--- a/lib/Sema/SemaLookup.cpp
+++ b/lib/Sema/SemaLookup.cpp
@@ -3000,7 +3000,7 @@
       // Walk through identifiers in external identifier sources.
       if (IdentifierInfoLookup *External
                               = Context.Idents.getExternalIdentifierLookup()) {
-        IdentifierIterator *Iter = External->getIdentifiers();
+        llvm::OwningPtr<IdentifierIterator> Iter(External->getIdentifiers());
         do {
           llvm::StringRef Name = Iter->Next();
           if (Name.empty())