Fbdev backend has been deprecated since weston 10.0.0, and it could be
replaced by passing --use-pixman to drm backend, add a use-pixman
PACKAGECONFIG for convenience.
(From OE-Core rev: e3dc3ee5e41caa1691ebdb1c6ed6e51077f9ce7a)
Signed-off-by: Ming Liu <liu.ming50@gmail.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>