Use hasCLanguageLinkage when warning about non C return types.

llvm-svn: 171263
diff --git a/clang/lib/Sema/SemaDecl.cpp b/clang/lib/Sema/SemaDecl.cpp
index c9d0c77..8d3abe7 100644
--- a/clang/lib/Sema/SemaDecl.cpp
+++ b/clang/lib/Sema/SemaDecl.cpp
@@ -6266,7 +6266,7 @@
     // If this function is declared as being extern "C", then check to see if 
     // the function returns a UDT (class, struct, or union type) that is not C
     // compatible, and if it does, warn the user.
-    if (NewFD->isExternC()) {
+    if (NewFD->hasCLanguageLinkage()) {
       QualType R = NewFD->getResultType();
       if (R->isIncompleteType() && !R->isVoidType())
         Diag(NewFD->getLocation(), diag::warn_return_value_udt_incomplete)