api.token.raw: fix it in C++

Another breakage revealed by vcsn.

* data/skeletons/c++.m4 (yytranslate_): Do not hard code "yy" and
"parser", both can be changed by the user.
Actually, since we are in the parser itself, there's really no need to
qualify the type.

data/skeletons/c++.m4

@@ -514,7 +514,7 @@ m4_define([b4_yytranslate_define],
   ]b4_parser_class[::yytranslate_ (int t)
   {
 ]b4_api_token_raw_if(
-[[    return static_cast<yy::parser::token_number_type> (t);]],
+[[    return static_cast<token_number_type> (t);]],
 [[    // YYTRANSLATE[TOKEN-NUM] -- Symbol number corresponding to
     // TOKEN-NUM as returned by yylex.
     static