In order to make wic images sparse sparse_copy function has been
copied from meta-ostro:
https://github.com/kad/meta-ostro/blob/master/meta-ostro/lib/image-dsk.py
This function uses filemap APIs to copy source sparse file into
destination file preserving sparseness.
The function has been modified to satisfy wic requirements:
parameter 'skip' has been added.
[YOCTO #9099]
Signed-off-by: Ed Bartosh <ed.bartosh@linux.intel.com> Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>
