vino-2.13.5 fails with current (avahi-0.6.{9,10}) versions of avahi because it is looking for avahi-client.pc, when the listed avahi versions only provide avahi-glib.pc and avahi-core.pc. Haven't had much time to look into the issue though.
avahi-client.pc gets installed with USE="dbus"
Created attachment 87159 [details] vino-2.13.5-r1.ebuild Ebuild now checks that avahi was built with dbus support. I suspect that this is going to be something common for avahi based software to have to do.
recompiled vino using this patch, no problem at compile time nor runtime. Please add it to the tree.
Fixes. Thanks for bringing this up.