avahi: fix avahi access through dbus

Ensure that the avahi dbus service gets installed if dbus support is
enabled, otherwise avahi access through dbus fails (as clients try
to start the daemon and dbus doesn't know how to do this).

Fixed upstream in 0.6.28 (http://avahi.org/ticket/319) but this
workaround is simpler/safer for now.

Signed-off-by: Peter Korsgaard <jacmet@sunsite.dk>

package/avahi/avahi.mk

@@ -160,8 +160,19 @@ define AVAHI_INSTALL_DAEMON_INITSCRIPT
 	$(INSTALL) -m 0755 package/avahi/S50avahi-daemon $(TARGET_DIR)/etc/init.d/
 endef
 
+# avahi build sys erroneously only installs dbus service if systemd is enabled
+define AVAHI_INSTALL_DAEMON_DBUS_SERVICE
+	$(INSTALL) -m 0644 -D $(@D)/avahi-daemon/org.freedesktop.Avahi.service \
+		$(TARGET_DIR)/usr/share/dbus-1/system-services/org.freedesktop.Avahi.service
+endef
+
 ifeq ($(BR2_PACKAGE_AVAHI_DAEMON),y)
 AVAHI_POST_INSTALL_TARGET_HOOKS += AVAHI_INSTALL_DAEMON_INITSCRIPT
+
+ifeq ($(BR2_PACKAGE_DBUS),y)
+AVAHI_POST_INSTALL_TARGET_HOOKS += AVAHI_INSTALL_DAEMON_DBUS_SERVICE
+endif
+
 endif
 
 $(eval $(call AUTOTARGETS,package,avahi))