dns-sd dll implementation -- Needs work

[Juan Lang]

Hi C.W.,

> I know there's probably a patches mailing list, but I put this here for feedback.

This is the appropriate place to ask about patches that aren't ready
to commit yet.

+#include <dns_sd.h>
At the least, you'll need to add configure checks for this header
file.  I imagine you'll need to load the library dynamically, too.  On
at least one of my systems, /usr/lib/libdns_sd.so is available, but
<dns_sd.h> is not.  I'm not sure how common that would be, but you
might want to provide a private copy of the .h file too.
--Juan