You can add one of them explicitly.

Add this in your spec
%if %suse_version > 1000
Requires:    mDNSResponder-lib

Ho and btw this should go into gnome-vfs spec, put this into mine (jarpack) and that issue went away on my repo (couple other package might depend on it explecitly too), i know this is kinda bad and keep avahi from being used at all but gnome-vfs WONT build with it at all and create a explicit dep on mDNSResponder.