res_rtp_asterisk: iterate all local addresses looking to populate ICE.

res_rtp_asterisk: iterate all local addresses looking to populate ICE.

By using pjproject to give us a list of candidates, and then filtering,
if the host has >32 addresses configured, then it is possible that we
end up filtering out all 32 of those, and ending up with no candidates
at all.  Instead, get getifaddrs (which pjsip is using underlying
anyway) to retrieve all local addresses, and iterate those, adding the
first 32 addresses not excluded by the ICE ACL.

In our setup at any point in time We've got between 6 and 328 addresses
on any given system.  The lower limit is the lower limit but the upper
limit is growing on a near daily basis currently.

Change-Id: I109eaffc3e2b432f00bf958e3caa0f38cacb4edb
Signed-off-by: Jaco Kroon <jaco@uls.co.za>