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/lzio.h

@@ -1,5 +1,5 @@
 /*
-** $Id: lzio.h $
+** $Id: lzio.h,v 1.26.1.1 2013/04/12 18:48:47 roberto Exp $
 ** Buffered streams
 ** See Copyright Notice in lua.h
 */
@@ -32,21 +32,20 @@ typedef struct Mbuffer {
 #define luaZ_sizebuffer(buff)	((buff)->buffsize)
 #define luaZ_bufflen(buff)	((buff)->n)
 
-#define luaZ_buffremove(buff,i)	((buff)->n -= (i))
 #define luaZ_resetbuffer(buff) ((buff)->n = 0)
 
 
 #define luaZ_resizebuffer(L, buff, size) \
-	((buff)->buffer = luaM_reallocvchar(L, (buff)->buffer, \
-				(buff)->buffsize, size), \
+	(luaM_reallocvector(L, (buff)->buffer, (buff)->buffsize, size, char), \
 	(buff)->buffsize = size)
 
 #define luaZ_freebuffer(L, buff)	luaZ_resizebuffer(L, buff, 0)
 
 
+LUAI_FUNC char *luaZ_openspace (lua_State *L, Mbuffer *buff, size_t n);
 LUAI_FUNC void luaZ_init (lua_State *L, ZIO *z, lua_Reader reader,
                                         void *data);
-LUAI_FUNC size_t luaZ_read (ZIO* z, void *b, size_t n);	/* read next n bytes */
+LUAI_FUNC size_t luaZ_read (ZIO* z, void* b, size_t n);	/* read next n bytes */
 
 
 
@@ -56,7 +55,7 @@ struct Zio {
   size_t n;			/* bytes still unread */
   const char *p;		/* current position in buffer */
   lua_Reader reader;		/* reader function */
-  void *data;			/* additional data */
+  void* data;			/* additional data */
   lua_State *L;			/* Lua state (for reader) */
 };