wic/engine: improve error reporting when using rm with wic
When trying to delete something from an ext partition using debugfs, we
don't show any error to the user when that operation fails.
Change this behavior to show the error generated by debugfs. Also,
fallback to use rmdir in case we are trying to delete a directory. However,
unlike mdeltree that is used for a FAT partition, there's no easy way to
delete a non empty directory. Show an error instead when that happens so
user can take appropriate action.
Signed-off-by: Anuj Mittal <anuj.mittal@intel.com> Signed-off-by: Ross Burton <ross.burton@intel.com>
