configure.in: deprecate -flat_namespace
git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@36573 b2dd03c8-39d4-4d8f-98ff-823fe69b080e
configure.in: deprecate -flat_namespace
rid of huge imported symbols table.
git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@36573 b2dd03c8-39d4-4d8f-98ff-823fe69b080e