osx: use bdist_mpkg.script_bdist_mpkg module instead of bdist_mpkg command It seems like a default installation of bdist_mpkg makes it available as Python module, but the corresponding executable is placed in a location like /System/Library/Frameworks/Python.framework/Versions/2.7/Extras/bin which is not in $PATH and thus not directly available. 'make osx' would thus fail. Instead, skip the bdist_mpkg executable and invoke it as a Python module. That works out of the box here.