Change to warning when property uses an ivar in super class
in an @synthesize diective, as it breaks few projects.

llvm-svn: 70441
diff --git a/clang/lib/Sema/SemaDeclObjC.cpp b/clang/lib/Sema/SemaDeclObjC.cpp
index 7eea4ff..170efec 100644
--- a/clang/lib/Sema/SemaDeclObjC.cpp
+++ b/clang/lib/Sema/SemaDeclObjC.cpp
@@ -1914,7 +1914,7 @@
     }
     else if (getLangOptions().ObjCNonFragileABI &&
              ClassDeclared != IDecl) {
-      Diag(PropertyLoc, diag::error_ivar_in_superclass_use)
+      Diag(PropertyLoc, diag::warn_ivar_in_superclass_use)
         << property->getDeclName() << Ivar->getDeclName() 
         << ClassDeclared->getDeclName();
       Diag(Ivar->getLocation(), diag::note_previous_access_declaration)