[new] audio/shairport-sync an AirPlay audio player

Hi,

Here is a port of shairport-sync. It lets one stream audio from iDevices
to OpenBSD.

DESCR snip:

Shairport Sync is an AirPlay audio player. It plays audio streamed from
iTunes, iOS, Apple TV and macOS devices and AirPlay sources such as Quicktime
Player and ForkedDaapd, among others.

HOME: https://github.com/mikebrady/shairport-sync

I have had this in WIP for some time and it has been working without a
hitch.

Cluesticks? OK to import?

Here is the diff for the user db:

diff 43179bcb078bb95ad600e5d85321b77ec70deb07 /usr/ports
blob - 17cb166abe6601b51e206bb97d1ce009a2729eac
file + infrastructure/db/user.list
--- infrastructure/db/user.list
+++ infrastructure/db/user.list
@@ -380,3 +380,4 @@ id user group port
869 _headscale _headscale net/headscale
870 _unit _unit www/unit
871 _gelatod _gelatod net/gelatod
+872 _shairport _shairport audio/shairport-sync