Installing wine with osxwinebuilder
I will hazard the guess that you need to install libtool.  You can do that with

brew install libtool
brew link libtool


From what I understand, libltdl is provided with that.
http://www.gnu.org/software/libtool/manual/html_node/Using-libltdl.html

I don't actually use homebrew so I hope that my stab in the dark helps you find your solution!