Ruby

transform_mjit_header.rb: refactor messages and exit

• tool/transform_mjit_header.rb: print non-error messages to
  STDOUT instead of STDERR. exit with false or abort instead of
  exit 1.

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@62205 b2dd03c8-39d4-4d8f-98ff-823fe69b080e