Point-to-Point interfaces regressions

[Li, Qing]

> 
> Me and many other people running net/mpd handling thousands of PtP
> interfaces sharing local addresses with each other and with some
> Ethernet interface. This change makes such setup inoperable, as mpd
> will constantly receive errors while trying to set addresses and 
> drop connections.
> 

  I can revert to the old behavior. I asked for feedback and received
  none at the time ...

  -- Qing