avahi: fix installed but not shipped warning

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>