[NEW PORT] lang/lua54 - Lua 5.4.1

Highlights for this version:

• new generational mode for garbage collection
• to-be-closed variables
• const variables
• complete list: https://www.lua.org/manual/5.4/readme.html#changes

The Lua Manual can be found here: https://www.lua.org/manual/5.4/

Incompatibilities from the previous version are specifically documented
here: https://www.lua.org/manual/5.4/manual.html#8

Submitted by: Russ Haley <russ haley gmail com>
Co-submitted by: Andrew Gierth <andrew_tao173 riddles org uk>
Differential Revision: https://reviews.freebsd.org/D14709