at the end of gethostanswer()/getanswer()/whatever where it used to
return TRY_AGAIN. This breaks the domain list traversal in ypserv's
async DNS lookup module: it would only retry using the domain(s) from
the 'domain' or 'search' lines in /etc/resolv.conf if __dns_getanswer()
returned TRY_AGAIN.
Changed the test so that either TRY_AGAIN or NO_RECOVERY will work.
This seemed to me the best solution in the event somebody tries to
compile this code on an older system with a different version of BIND.
(You shouldn't do that of course, but then there's a lot of things
in the world that you shouldn't do and people do them anyway.)