Bring Lua to 5.4.6. (#1214)

This essentially re-does the work of #875 on top of master.

This is what I did to check that Cosmo's Lua extensions still worked:

```
$ build/bootstrap/make MODE=aarch64 o/aarch64/third_party/lua/lua
$ ape o/aarch64/third_party/lua/lua
>: 10
10
>: 010
8
>: 0b10
2
>: string.byte("\e")
27
>: "Hello, %s" % {"world"}
Hello, world
>: "*" * 3
***
```

`luaL_traceback2` was used to show the stack trace with parameter
values; it's used in `LuaCallWithTrace`, which is used in Redbean to run
Lua code. You should be able to see the extended stack trace by running
something like this: `redbean -e "function a(b)c()end a(2)"` (with
"params" indicating the extended stack trace):

```
stack traceback:
 [string "function a(b)c()end a(2)"]:1: in function 'a', params: b = 2;
 [string "function a(b)c()end a(2)"]:1: in main chunk
```
@pkulchenko confirmed that I get the expected result with the updated
code.

This is what I did to check that Lua itself still worked:

```
$ cd third_party/lua/test/
$ ape ../../../o/aarch64/third_party/lua/lua all.lua
```

There's one test failure, in `files.lua`:

```
***** FILE 'files.lua'*****
testing i/o
../../../o/aarch64/third_party/lua/lua: files.lua:84: assertion failed!
stack traceback:
[C]: in function 'assert'
files.lua:84: in main chunk
(...tail calls...)
all.lua:195: in main chunk
[C]: in ?
.>>> closing state <<<
```

That isn't a result of these changes; the same test is failing in
master.

The failure is here:

```lua
if not _port then   -- invalid seek
  local status, msg, code = io.stdin:seek("set", 1000)
  assert(not status and type(msg) == "string" and type(code) == "number")
end
```

The test expects a seek to offset 1,000 on stdin to fail — but it
doesn't. `status` ends up being the new offset rather than `nil`.

If I comment out that one test, the remaining tests succeed.

third_party/lua/lmem.c

@@ -3,7 +3,7 @@
 ╚──────────────────────────────────────────────────────────────────────────────╝
 │                                                                              │
 │  Lua                                                                         │
-│  Copyright © 2004-2021 Lua.org, PUC-Rio.                                     │
+│  Copyright © 2004-2023 Lua.org, PUC-Rio.                                     │
 │                                                                              │
 │  Permission is hereby granted, free of charge, to any person obtaining       │
 │  a copy of this software and associated documentation files (the             │
@@ -27,6 +27,7 @@
 ╚─────────────────────────────────────────────────────────────────────────────*/
 #define lmem_c
 #define LUA_CORE
+
 #include "libc/log/log.h"
 #include "third_party/lua/ldebug.h"
 #include "third_party/lua/ldo.h"
@@ -39,26 +40,6 @@
 __static_yoink("lua_notice");
 
 
-#if defined(EMERGENCYGCTESTS)
-/*
-** First allocation will fail whenever not building initial state.
-** (This fail will trigger 'tryagain' and a full GC cycle at every
-** allocation.)
-*/
-static void *firsttry (global_State *g, void *block, size_t os, size_t ns) {
-  if (completestate(g) && ns > 0)  /* frees never fail */
-    return NULL;  /* fail */
-  else  /* normal allocation */
-    return (*g->frealloc)(g->ud, block, os, ns);
-}
-#else
-#define firsttry(g,block,os,ns)    ((*g->frealloc)(g->ud, block, os, ns))
-#endif
-
-
-
-
-
 /*
 ** About the realloc function:
 ** void *frealloc (void *ud, void *ptr, size_t osize, size_t nsize);
@@ -77,6 +58,43 @@ static void *firsttry (global_State *g, void *block, size_t os, size_t ns) {
 */
 
 
+/*
+** Macro to call the allocation function.
+*/
+#define callfrealloc(g,block,os,ns)    ((*g->frealloc)(g->ud, block, os, ns))
+
+
+/*
+** When an allocation fails, it will try again after an emergency
+** collection, except when it cannot run a collection.  The GC should
+** not be called while the state is not fully built, as the collector
+** is not yet fully initialized. Also, it should not be called when
+** 'gcstopem' is true, because then the interpreter is in the middle of
+** a collection step.
+*/
+#define cantryagain(g)	(completestate(g) && !g->gcstopem)
+
+
+
+
+#if defined(EMERGENCYGCTESTS)
+/*
+** First allocation will fail except when freeing a block (frees never
+** fail) and when it cannot try again; this fail will trigger 'tryagain'
+** and a full GC cycle at every allocation.
+*/
+static void *firsttry (global_State *g, void *block, size_t os, size_t ns) {
+  if (ns > 0 && cantryagain(g))
+    return NULL;  /* fail */
+  else  /* normal allocation */
+    return callfrealloc(g, block, os, ns);
+}
+#else
+#define firsttry(g,block,os,ns)    callfrealloc(g, block, os, ns)
+#endif
+
+
+
 
 
 /*
@@ -149,7 +167,7 @@ l_noret luaM_toobig (lua_State *L) {
 void luaM_free_ (lua_State *L, void *block, size_t osize) {
   global_State *g = G(L);
   lua_assert((osize == 0) == (block == NULL));
-  (*g->frealloc)(g->ud, block, osize, 0);
+  callfrealloc(g, block, osize, 0);
   g->GCdebt -= osize;
 }
 
@@ -157,20 +175,16 @@ void luaM_free_ (lua_State *L, void *block, size_t osize) {
 /*
 ** In case of allocation fail, this function will do an emergency
 ** collection to free some memory and then try the allocation again.
-** The GC should not be called while state is not fully built, as the
-** collector is not yet fully initialized. Also, it should not be called
-** when 'gcstopem' is true, because then the interpreter is in the
-** middle of a collection step.
 */
 static void *tryagain (lua_State *L, void *block,
                        size_t osize, size_t nsize) {
   global_State *g = G(L);
-  if (completestate(g) && !g->gcstopem) {
-    WARNF("reacting to malloc() failure by running lua garbage collector...");
+  if (cantryagain(g)) {
+    WARNF("reacting to malloc() failure by running lua garbage collector...");  // [jart]
     luaC_fullgc(L, 1);  /* try to free some memory... */
-    return (*g->frealloc)(g->ud, block, osize, nsize);  /* try again */
+    return callfrealloc(g, block, osize, nsize);  /* try again */
   }
-  else return NULL;  /* cannot free any memory without a full state */
+  else return NULL;  /* cannot run an emergency collection */
 }