LUA: Fix CVE-2014-5461

Apply the fix from upstream.

http://www.lua.org/bugs.html#5.2.2-1
https://www.opencve.io/cve/CVE-2014-5461

It should be noted that exploiting this requires the SYS_CONFIG
privilege, and anyone with that privilege likely has other opportunities
to do exploits, so it is unlikely that bad actors could exploit this
unless system administrators are executing untrusted ZFS Channel
Programs.

Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Signed-off-by: Richard Yao <richard.yao@alumni.stonybrook.edu>
Closes #13949