* benchmark/bm_app_answer.rb: revert r42990, benchmark scripts should
  be self-contained and avoid dependencies, especially such small one.
  See https://github.com/ruby/ruby/pull/393#issuecomment-24861301.

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@43012 b2dd03c8-39d4-4d8f-98ff-823fe69b080e