osx: create a modern package including manpages Instead of using bdist_mpkg, we use the modern Apple-provided tools to build an OS X Installer package directly. This has several advantages: * Avoids bdist_mpkg which seems to be barely maintained and is hard to use. * Creates a single unified .pkg instead of a .mpkg. * The package we produce is in the modern, single-file format instead of a directory bundle that we have to zip up for download. In addition, this way of building the package now correctly: * Installs the manpages, bringing the `make osx`-generated package in line with the official Mac packages we publish on the website. * Installs files with the correct permissions instead of encoding the UID of the user who happened to build the package. Thanks to Augie for updating the test expectations.