spa_config_load() passes NULL into resid when doing zfs_file_read().
This would trip over when vfs.zfs.autoimport_disable=0.
Sponsored by: The FreeBSD Foundation
Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Reviewed-by: Allan Jude <allan@klarasystems.com>
Signed-off-by: Ka Ho Ng <khng@freebsdfoundation.org>
Closes#11149