Add support for multiple entries in bind_addr, e.g.

  bind_addr="match-interface:eth2,10.5.5.5,match-interface:en*,127.0.0.1"

This would try to bind to eth2 first. If not found, then an interface with address 10.5.5.5 would be tried, then an interface starting with en would be tried. If still not found, we'd bind to 127.0.0.1.