Attached patches fix list of installed files forr various combinations of switches.
avahi-man-selection.patch: Install only man pages to installed binaries.
avahi-no-gtk-no-interfaces.patch: Do not install glade interfaces file, if no gtk is present.
avahi-bookmarks-no-pygtk.patch: Install avahi bookmarks, even if no pygtk is available.
Note: It is still far from sufficient to build system without avahi -> cups -> gtk -> avahi build cycle without a lot of effort.
Over the time, avahi become core part of system, and dependence on gtk2 is not acceptable.
I would propose to split avahi to several sub-projects. openSUSE currently uses:
avahi-core
avahi compat libraries (several subpackages)
avahi-python
avahi-python-gtk
avahi-utils
avahi-utils-gtk
avahi-glib
avahi-qt3
avahi-qt4
avahi-mono