Fixes:
WARNING: Unable to get checksum for libart-lgpl SRC_URI entry art_config.h: file could not be found
which otherwise happens during parsing, even if libart-lgpl isn't being built.
(From OE-Core rev: a9245e0d1dd1bee4ac01fe0c73d95179033ba979)
Signed-off-by: Phil Blundell <philb@gnu.org>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>