Enable shellcheck to run for select scripts
Enable shellcheck to run on zed scripts,
paxcheck.sh, zfs-tests.sh, zfs.sh, and zloop.sh.
Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Reviewed-by: Tony Hutter <hutter2@llnl.gov>
Signed-off-by: Giuseppe Di Natale <dinatale2@llnl.gov>
Closes #5812