[OE-core] Creating cpio images with support for xattrs

[Andre McCurdy]

Currently we create cpio rootfs images using the standard cpio tool.
However that doesn't support the extensions added to the cpio format
by the kernel in order to support initramfs images with xattrs:

  https://lwn.net/Articles/629134/

It looks like the only tool which does support these cpio extensions
is the one in the kernel source tree ( usr/gen_init_cpio.c ). Assuming
that's true, has anyone already tried to update the cpio image type to
use the kernel cpio tools?