Log Message:
net/tut: Fix beeep dependency on Illumos

There were two issues with dependency 'beeep':

 1. The 'unix' backends weren't selected for Illumos
    https://github.com/gen2brain/beeep/pull/54

 2. The fallback 'unsupported' backend had a signature mismatch:
    https://github.com/gen2brain/beeep/pull/53

Both were fixed in a patched fork at https://github.com/sjmulder/beeep,
which is used here. Once the issue is fixed upstream the original
dependencies can be used again.