These include files are really required, not optional.
(From OE-Core rev: 1aa6c4a083e406de0119f92e9654068d6cc2e4de)
Signed-off-by: Damien Lespiau <damien.lespiau@intel.com>
Signed-off-by: Ross Burton <ross.burton@intel.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>