feat: 适配 Lua 5.2.4 (lua_5.2.4 分支)

- lib/lua 替换为 Lua 5.2.4 官方源码; CMakeLists 补 lbitlib.c(5.2 linit 注册 bit32)、删 lutf8lib.c(5.2 无此文件)
- I/O 重定向机制改造: 5.2 无 lua_getextraspace → iopath 指针存入
  Registry 固定索引(IOPATH_REG_IDX=1), 回调经 get_iopath() 取回,
  free_lua 时释放 —— 该方案同样适用于更低版本
- typed interop 版本自适应: capture_result() 的 lua_isinteger 分支用
  #if LUA_VERSION_NUM >= 503 包裹, 5.2 及以下所有数字统一 CJT_NUM
- 测试跨版本适配: PackagePathConfig 接受 require 的两种返回语义;
  typed 数值断言 EXPECT_INT_OR_NUM 宏兼容有无 integer 子类型;
  大整数保真断言仅对 5.3+ 生效(5.2 经 double 必然丢精度)
- 验证: GTest 44/44 通过

lib/lua/lstring.h

@@ -1,5 +1,5 @@
 /*
-** $Id: lstring.h $
+** $Id: lstring.h,v 1.49.1.1 2013/04/12 18:48:47 roberto Exp $
 ** String table (keep all strings handled by Lua)
 ** See Copyright Notice in lua.h
 */
@@ -12,46 +12,35 @@
 #include "lstate.h"
 
 
-/*
-** Memory-allocation error message must be preallocated (it cannot
-** be created after memory is exhausted)
-*/
-#define MEMERRMSG       "not enough memory"
+#define sizestring(s)	(sizeof(union TString)+((s)->len+1)*sizeof(char))
 
-
-/*
-** Size of a TString: Size of the header plus space for the string
-** itself (including final '\0').
-*/
-#define sizelstring(l)  (offsetof(TString, contents) + ((l) + 1) * sizeof(char))
+#define sizeudata(u)	(sizeof(union Udata)+(u)->len)
 
 #define luaS_newliteral(L, s)	(luaS_newlstr(L, "" s, \
                                  (sizeof(s)/sizeof(char))-1))
 
+#define luaS_fix(s)	l_setbit((s)->tsv.marked, FIXEDBIT)
+
 
 /*
 ** test whether a string is a reserved word
 */
-#define isreserved(s)	((s)->tt == LUA_VSHRSTR && (s)->extra > 0)
+#define isreserved(s)	((s)->tsv.tt == LUA_TSHRSTR && (s)->tsv.extra > 0)
 
 
 /*
 ** equality for short strings, which are always internalized
 */
-#define eqshrstr(a,b)	check_exp((a)->tt == LUA_VSHRSTR, (a) == (b))
+#define eqshrstr(a,b)	check_exp((a)->tsv.tt == LUA_TSHRSTR, (a) == (b))
 
 
 LUAI_FUNC unsigned int luaS_hash (const char *str, size_t l, unsigned int seed);
-LUAI_FUNC unsigned int luaS_hashlongstr (TString *ts);
 LUAI_FUNC int luaS_eqlngstr (TString *a, TString *b);
+LUAI_FUNC int luaS_eqstr (TString *a, TString *b);
 LUAI_FUNC void luaS_resize (lua_State *L, int newsize);
-LUAI_FUNC void luaS_clearcache (global_State *g);
-LUAI_FUNC void luaS_init (lua_State *L);
-LUAI_FUNC void luaS_remove (lua_State *L, TString *ts);
-LUAI_FUNC Udata *luaS_newudata (lua_State *L, size_t s, int nuvalue);
+LUAI_FUNC Udata *luaS_newudata (lua_State *L, size_t s, Table *e);
 LUAI_FUNC TString *luaS_newlstr (lua_State *L, const char *str, size_t l);
 LUAI_FUNC TString *luaS_new (lua_State *L, const char *str);
-LUAI_FUNC TString *luaS_createlngstrobj (lua_State *L, size_t l);
 
 
 #endif