Implement N4051 - Allow typename in a template template parameter

[Jason Merrill]

On 07/22/2014 01:53 PM, Ed Smith-Rowland wrote:
> +	if (cxx_dialect < cxx1z)
> +	  {
> +	    /* Look for the `class' keyword.  */
> +	    cp_parser_require_keyword (parser, RID_CLASS, RT_CLASS);
> +	  }
> +	else
> +	  {
> +	    /* Look for the `class' or 'typename' keywords.  */
> +	    enum tag_types tag_type = cp_parser_type_parameter_key (parser);
> +	    if (tag_type == none_type)
> +	      return error_mark_node;
> +	  }

Let's encapsulate this in cp_parser_type_parameter_key.  And also accept 
'typename' in lower dialects with a pedwarn.

Jason