Remove deprecated rbconfig/datadir

This is deleted at
0e3c2c1f04
in upstream.

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@57386 b2dd03c8-39d4-4d8f-98ff-823fe69b080e

doc/maintainers.rdoc

@@ -120,8 +120,6 @@ Zachary Scott (zzak)
   _unmaintained_
 [lib/racc/*]
   Aaron Patterson (tenderlove)
-[lib/rbconfig/*]
-  _unmaintained_
 [lib/rdoc.rb, lib/rdoc/*]
   Eric Hodel (drbrain), Hiroshi SHIBATA (hsbt)
 [lib/resolv-replace.rb]

lib/rbconfig/.document

@@ -1 +0,0 @@
-# these files are obsolete

lib/rbconfig/datadir.rb

@@ -1,14 +0,0 @@
-# frozen_string_literal: false
-#--
-# Copyright 2006 by Chad Fowler, Rich Kilmer, Jim Weirich and others.
-# All rights reserved.
-# See LICENSE.txt for permissions.
-#++
-
-# N.B. This file is used by Config.datadir in rubygems.rb, and must not be
-# removed before that require is removed. I require to avoid warning more than
-# once.
-
-warn 'rbconfig/datadir.rb and {Rb}Config.datadir is being deprecated from '\
- 'RubyGems. It will be removed completely on or after June 2011. If you '\
- 'wish to rely on a datadir, please use Gem.datadir.'