Clean up (k)shlib and cfg file shebangs

Clean up (k)shlib and cfg file shebangs

Most kshlib files are imported by other scripts
and do not have a shebang at the top of their files.
Make all kshlib follow this convention.

Remove shebangs from cfg files as well.

Reviewed-by: loli10K <ezomori.nozomu@gmail.com>
Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Signed-off-by: Giuseppe Di Natale <dinatale2@llnl.gov>
Close #7406