Fix indentation.
Document new flags, fix typo.
Make pcap_if_sort() static and get rid of unused variables.

pcap_if_sort() isn't used outside this file, so make it static.

Clean up indentation while we're at it.
Don't exclude interfaces that aren't up.

On some platforms, you can capture on those interfaces, which might be
useful if you want to start a capture before the interface is up, so
that the capture starts capturing as soon as it's up.

Those interfaces will not appear in the interface list on platforms
where you can't open them for capturing, and they'll now be sorted after
the interfaces that *are* up, so there's not much harm in including
them.
Return the value of pcap_add_if() from septel_findalldevs().

That way, errors are reflected to the caller.

Also, just pass strings directly to pcap_add_if(), and get rid of unused
variables.
Pull the code to add an address to an interface into a routine.

Call that routine from fad-win32.c, rather than duplicating the code.
Don't lose the addresses for interfaces.

pcap_add_if() doesn't add addresses; instead of the existing sort code
called by pcap_findalldevs(), change the code for inserting interfaces
into the list to use a "figure of merit" that takes the running, up, and
loopback bits into account, as well as the number from the interface
name, rather than just the interface name, into account.
Another check for IFF_UP removed.