parse_interface() fails on "eth0" with Ubuntu 14.04 about openpgm HOT 3 OPEN

Versions: libc 2.19-0ubuntu3, kernel 3.13.0-20-generic.

Thanks, I was surprised to never see this error code in the wild even with bad 
DNS servers or mDNS.  Will update trunk.

Actually, I'm not sure it is sensible to hide such an subsystem failure within 
the API.  It would be more apparent if the application calling 
pgm_getaddrinfo() captures the error domain PGM_ERROR_DOMAIN_IF and code 
PGM_ERROR_AGAIN and determines how it should proceed.

One possible enhancement would be an option equivalent to AI_NUMERICHOST so 
that network services are not used however one has no control over system name 
services whether they be local or remote based.  So the flag would have to 
disable pgm_getnetbyname() and getaddrinfo(~AI_NUMERICHOST).

Alternatively of course, just use a /etc/networks name or IP address of the 
interface.