cups: Add --with-dbusdir to EXTRA_OECONF for deterministic build

cups: Add --with-dbusdir to EXTRA_OECONF for deterministic build

The configure checks /etc/dbus-1 and set DBUSDIR is null:
        if test -d /etc/dbus-1 -a "x$DBUSDIR" = x; then
            DBUSDIR="/etc/dbus-1"
        fi

So that the build resutl would be different w/o /etc/dbus-1:

/etc/dbus-1/system.d/cups.conf (Only exists when DBUSDIR is set)

Add --with-dbusdir to EXTRA_OECONF to fix the issue

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