Remove the ref/value inconsistency in filter_decl_iterator.

filter_decl_iterator had a weird mismatch where both op* and op-> returned T*
making it difficult to generalize this filtering behavior into a reusable
library of any kind.

This change errs on the side of value, making op-> return T* and op* return
T&.

(reviewed by Richard Smith)

llvm-svn: 155808
diff --git a/clang/lib/AST/ASTImporter.cpp b/clang/lib/AST/ASTImporter.cpp
index 3879907..6ecc489 100644
--- a/clang/lib/AST/ASTImporter.cpp
+++ b/clang/lib/AST/ASTImporter.cpp
@@ -1017,7 +1017,7 @@
       return false;
     }
     
-    if (!IsStructurallyEquivalent(Context, *Field1, *Field2))
+    if (!IsStructurallyEquivalent(Context, &*Field1, &*Field2))
       return false;    
   }