Unbreak gcc build.

For some reason clang and msvc accept this, but gcc doesn't.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@143872 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Sema/SemaPseudoObject.cpp b/lib/Sema/SemaPseudoObject.cpp
index e0a6271..4dc6a18 100644
--- a/lib/Sema/SemaPseudoObject.cpp
+++ b/lib/Sema/SemaPseudoObject.cpp
@@ -106,7 +106,7 @@
   struct ObjCPropertyRefRebuilder : Rebuilder<ObjCPropertyRefRebuilder> {
     Expr *NewBase;
     ObjCPropertyRefRebuilder(Sema &S, Expr *newBase)
-      : Rebuilder(S), NewBase(newBase) {}
+      : Rebuilder<ObjCPropertyRefRebuilder>(S), NewBase(newBase) {}
 
     typedef ObjCPropertyRefExpr specific_type;
     Expr *rebuildSpecific(ObjCPropertyRefExpr *refExpr) {