This adds support for NetBSD, using the following external dependencies: libuuid ncursesw There is no CI (yet) as enabling that on Cirrus-CI requires some work, so for now, these builds will be run manually before releases. The test suite will also need tweaking to be fully supported but the key tests are supported for now.

This adds support for MacOS (Monteray onward, although should work on older MacOSes). The BSD wrapper for poll/ppoll has been lifted from the work the folks over at OpenSSH have done -- thanks!