Keep track of an @implementation's super class name location, if one was provided.

llvm-svn: 181039
diff --git a/clang/lib/Serialization/ASTWriterDecl.cpp b/clang/lib/Serialization/ASTWriterDecl.cpp
index b7ca623..ef50cdba 100644
--- a/clang/lib/Serialization/ASTWriterDecl.cpp
+++ b/clang/lib/Serialization/ASTWriterDecl.cpp
@@ -613,6 +613,7 @@
 void ASTDeclWriter::VisitObjCImplementationDecl(ObjCImplementationDecl *D) {
   VisitObjCImplDecl(D);
   Writer.AddDeclRef(D->getSuperClass(), Record);
+  Writer.AddSourceLocation(D->getSuperLoc(), Record);
   Writer.AddSourceLocation(D->getIvarLBraceLoc(), Record);
   Writer.AddSourceLocation(D->getIvarRBraceLoc(), Record);
   Record.push_back(D->hasNonZeroConstructors());