kwrest arg name

	* compile.c (iseq_set_arguments_keywords): make keyword rest
	  argument name nd_vid consistently, regardless of whether other
	  keyword arguments are present.  [Fix GH-1529]

	* parse.y (new_args_tail_gen): ditto.

	fix nd_ainfo->kw_rest_arg

	[Fix GH-5129]
	Author:    fate0 <fate0@users.noreply.github.com>

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/branches/ruby_2_4@62444 b2dd03c8-39d4-4d8f-98ff-823fe69b080e