Pick up a few bug fixes from lua 5.4.8:

267ef461 Bug: check for constructor overflow in [exp] fields
d1ee2a4d Bug: Bad error message with fields of string _ENV
3fe7be95 Bug: message handler can be overwritten
983bc433 Bug: Use after free in 'luaV_finishset'
25da574f Bug: 'luaD_seterrorobj' should not raise errors
f5e55be2 Bug: Missing error status in panic function
9f0c0fe0 Bug: Wrong limit for local variables in 16-bit systems
782ef85b Bug: wrong code gen. for indices with comparisons
30982bec Bug: Bad stack manipulation in 'multiline' (REPL)

This is a bug fix to Lua 5.4.4 (5.4.5 was withdrawn due to ABI issues
and 5.4.6 is 5.4.5 with those fixed).

Merge commit '755d9301ca89f02956fd17858b9d4d821ab5c972' from the
vendor branch. This updates us from lua 5.4.2 to 5.4.4.

In addition, it switches around how we flavor liblua for the boot loader
and flua. This is done to reduce diffs with upstream and make it easier
to import new versions (the current method has too many conflicts to
resolve by hand): we include luaconf.local.h from luaconf.h (the only
change to this file is now that #include at the end). We then define
what we need to: for flua (which does very little) and one for stand
(which creates the new FLOAT type out of int64).

Sponsored by:		Netflix

Merge commit '0ea45b9cd43ce1247eb3eee9bfd5cee3d19068e7' into main

This release contains some minor bugfixes; notably:
- 2x minor Makefile fixes (not used in base)
- Long brackets with a huge number of '=' overflow some internal buffer
  arithmetic.
- Joining an upvalue with itself can cause a use-after-free crash.

See here for examples: http://www.lua.org/bugs.html#5.3.5

MFC after:	2 weeks

Bugfix release, nothing too major.

Tested with:	lualoader via userboot, lualoader live
Differential Revision:	https://reviews.freebsd.org/D16665