are resolved by r38096. r38096 removed GEM_SKIP configuration.

  The below is ChangeLog of r38053:

* defs/default_gems: Add base directory column.

* tool/rbinstall.rb:
  - Install .gemspecs of default gem to
    #{GEM_HOME}/specifications/default/.
  - Update files parameter of .gemspecs by relative path from
    library directory.


git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@38101 b2dd03c8-39d4-4d8f-98ff-823fe69b080e