* lib/xmlrpc/parser.rb: added new parser class using libxml-ruby gem.
  [Feature #9379][ruby-core:59633]
* lib/xmlrpc/config.rb: ditto.

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@47902 b2dd03c8-39d4-4d8f-98ff-823fe69b080e