using RTLD_NEXT. [ruby-dev:38152] * ext/dl/handle.c (Init_dlhandle): added constants DEFAULT and NEXT which correspond to RTLD_DEFAULT and RTLD_NEXT. git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@23551 b2dd03c8-39d4-4d8f-98ff-823fe69b080e