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/linit.c

@@ -1,33 +1,20 @@
 /*
-** $Id: linit.c $
+** $Id: linit.c,v 1.32.1.1 2013/04/12 18:48:47 roberto Exp $
 ** Initialization of libraries for lua.c and other clients
 ** See Copyright Notice in lua.h
 */
 
 
-#define linit_c
-#define LUA_LIB
-
 /*
 ** If you embed Lua in your program and need to open the standard
 ** libraries, call luaL_openlibs in your program. If you need a
 ** different set of libraries, copy this file to your project and edit
 ** it to suit your needs.
-**
-** You can also *preload* libraries, so that a later 'require' can
-** open the library, which is already linked to the application.
-** For that, do the following code:
-**
-**  luaL_getsubtable(L, LUA_REGISTRYINDEX, LUA_PRELOAD_TABLE);
-**  lua_pushcfunction(L, luaopen_modname);
-**  lua_setfield(L, -2, modname);
-**  lua_pop(L, 1);  // remove PRELOAD table
 */
 
-#include "lprefix.h"
 
-
-#include <stddef.h>
+#define linit_c
+#define LUA_LIB
 
 #include "lua.h"
 
@@ -40,26 +27,41 @@
 ** program
 */
 static const luaL_Reg loadedlibs[] = {
-  {LUA_GNAME, luaopen_base},
+  {"_G", luaopen_base},
   {LUA_LOADLIBNAME, luaopen_package},
   {LUA_COLIBNAME, luaopen_coroutine},
   {LUA_TABLIBNAME, luaopen_table},
   {LUA_IOLIBNAME, luaopen_io},
   {LUA_OSLIBNAME, luaopen_os},
   {LUA_STRLIBNAME, luaopen_string},
+  {LUA_BITLIBNAME, luaopen_bit32},
   {LUA_MATHLIBNAME, luaopen_math},
-  {LUA_UTF8LIBNAME, luaopen_utf8},
   {LUA_DBLIBNAME, luaopen_debug},
   {NULL, NULL}
 };
 
 
+/*
+** these libs are preloaded and must be required before used
+*/
+static const luaL_Reg preloadedlibs[] = {
+  {NULL, NULL}
+};
+
+
 LUALIB_API void luaL_openlibs (lua_State *L) {
   const luaL_Reg *lib;
-  /* "require" functions from 'loadedlibs' and set results to global table */
+  /* call open functions from 'loadedlibs' and set results to global table */
   for (lib = loadedlibs; lib->func; lib++) {
     luaL_requiref(L, lib->name, lib->func, 1);
     lua_pop(L, 1);  /* remove lib */
   }
+  /* add open functions from 'preloadedlibs' into 'package.preload' table */
+  luaL_getsubtable(L, LUA_REGISTRYINDEX, "_PRELOAD");
+  for (lib = preloadedlibs; lib->func; lib++) {
+    lua_pushcfunction(L, lib->func);
+    lua_setfield(L, -2, lib->name);
+  }
+  lua_pop(L, 1);  /* remove _PRELOAD table */
 }