Pack UsingDecl more.

88 -> 80 bytes on x86_64.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@147736 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Serialization/ASTWriterDecl.cpp b/lib/Serialization/ASTWriterDecl.cpp
index 45ce779..46e251b 100644
--- a/lib/Serialization/ASTWriterDecl.cpp
+++ b/lib/Serialization/ASTWriterDecl.cpp
@@ -862,7 +862,7 @@
   Writer.AddSourceLocation(D->getUsingLocation(), Record);
   Writer.AddNestedNameSpecifierLoc(D->getQualifierLoc(), Record);
   Writer.AddDeclarationNameLoc(D->DNLoc, D->getDeclName(), Record);
-  Writer.AddDeclRef(D->FirstUsingShadow, Record);
+  Writer.AddDeclRef(D->FirstUsingShadow.getPointer(), Record);
   Record.push_back(D->isTypeName());
   Writer.AddDeclRef(Context.getInstantiatedFromUsingDecl(D), Record);
   Code = serialization::DECL_USING;