Otherwise the class doesn't work if ${bindir} is set to a different value;
likewise for /var vs ${localstatedir}.
(From OE-Core rev: 21371df16917cd82642b39763793783d61ee5516)
Signed-off-by: Phil Blundell <philb@gnu.org>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>