If there is no BBLAYERS set in bblayers.conf show a more helpful
error and exit.
[YOCTO #14340]
(Bitbake rev: 7f7034a6a0893debd8a5288a5765146a8b2ab0a0)
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>
(cherry picked from commit 97183e10faf9862b5d9489d6e2c27ac77c3b697d)
Signed-off-by: Steve Sakoman <steve@sakoman.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>