MFH: r414062

net-mgmt/unifi4: Add a LOCAL mirror for the distfiles

Sometimes Ubiquiti updates and pulls old versions for no obvious reason and
this causes the quarterly branch build process to repeatedly email me
with errors. The license for Unifi does not restrict hosting copies of
the distfile, so I will use a backup mirror will solve this.

Approved by: ports-secteam (with hat)