abisip-find: Improve use information output

Interestingly, SO_BINDTODEVICE used to bind to a specific iface
requires root permissions. However, the same target can be accomplished
by binding to a local IP addr set on the target interface, which doesn't
require root permissions in this case.

Change-Id: Ie123c45005d68b186cb06538f7bd31f3b2513007
1 file changed