Hi,
I am using transmission from macports and recently found that the build is broken. I initially filed a ticket for investigation with macports here:
https://trac.macports.org/ticket/52749
However, as per comment 4, it seems like the build was broken some time around version 2.90 of transmission with the changes referenced here:
https://trac.macports.org/ticket/52749#comment:4
This seems to be trivial to fix (basically undo that change so that the version of libcrypto you link against is not fixed to something specific).