specify an open flag. (Init_dbm): define open flags: DBM::READER, DBM::WRITER, DBM::WRCREAT and DBM::NEWDB. git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@6326 b2dd03c8-39d4-4d8f-98ff-823fe69b080e
git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@6264 b2dd03c8-39d4-4d8f-98ff-823fe69b080e