avahi: fix installed but not shipped warning

The avahi recipe has a warning when build without systemd feature:

WARNING: QA Issue: avahi: Files/directories were installed but not shipped
  /usr/share/dbus-1

The /usr/share/dbus-1 is empty without systemd feature, there would be
/usr/share/dbus-1/system-services with systemd. Use rmdir to fix the
problem, and remove the ${datadir}/dbus-1/interfaces from the FILES list
which had been removed clearly by the do_install.

[YOCTO #3939]

(From OE-Core rev: 51cfcef15b59f7b97c871d9c0d6bf560c7b06c9b)

Signed-off-by: Robert Yang <liezhi.yang@windriver.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>

meta/recipes-connectivity/avahi/avahi.inc

@@ -90,7 +90,6 @@ FILES_avahi-daemon = "${sbindir}/avahi-daemon \
                       ${datadir}/avahi/introspection/*.introspect \
                       ${datadir}/avahi/avahi-service.dtd \
                       ${datadir}/avahi/service-types \
-                      ${datadir}/dbus-1/interfaces \
                       ${datadir}/dbus-1/system-services"
 FILES_libavahi-client = "${libdir}/libavahi-client.so.*"
 FILES_libavahi-ui = "${libdir}/libavahi-ui.so.*"
@@ -128,6 +127,7 @@ do_install() {
 	# if /var/run become non-empty in the future, need to install it via volatile
 	rm -rf ${D}/var/run
 	rm -rf ${D}${datadir}/dbus-1/interfaces
+	rmdir --ignore-fail-on-non-empty ${D}${datadir}/dbus-1
 	rm -rf ${D}${libdir}/avahi
 
 	install -d ${D}${sysconfdir}/udhcpc.d