extrernalsrc.bbclass: treat kernel meta like local source
Kernel metadata repository needs to be fetched/unpacked into the work
directory in order to build the kernel. Sources pointing to a remote
location are skipped by externalsrc by default which caused kernel build
to fail (because of remote kernel-meta was not made availeble). This
patch will make kernel-meta always available.
[YOCTO #6658]
Signed-off-by: Markus Lehtonen <markus.lehtonen@linux.intel.com> Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>
