Find libboost_python3-mt.dylib installed by MacPorts
Find libboost_python3-mt.dylib installed by MacPorts

MacPorts will install Boost-Python as something like the following
(for Python 3.5) when runng `port install boost +python35`:
/opt/local/lib/libboost_python3-mt.dylib

This library won't otherwise be found with the existing suffixes.

osmcode/pyosmium,osmcode/pyosmium,osmcode/pyosmium