Fix incorrect separator when generating tag type

Module and type names with '_', e.g. 'Test_Module::A_Type' were
generating incorrect tags that did not align with the use of '::'
elsewhere, with result compile failures.

dds/idl/metaclass_generator.cpp

@@ -473,7 +473,7 @@ void generate_anon_fields(AST_Structure* node)
               post = "_forany";
             } else if (use_cxx11 && (elem_cls & (CL_ARRAY | CL_SEQUENCE))) {
               pre = "IDL::DistinctType<";
-              post = ", " + dds_generator::get_tag_name(dds_generator::scoped_helper(deepest_named_type(elem_orig)->name(), "_")) + ">";
+              post = ", " + dds_generator::get_tag_name(dds_generator::scoped_helper(deepest_named_type(elem_orig)->name(), "::")) + ">";
             }
             be_global->impl_ <<
               "    if (!gen_skip_over(ser, static_cast<" << pre << cxx_elem << post