feat: 适配 Lua 5.1.5 (lua_5.1.5 分支)

- lib/lua 替换为 Lua 5.1.5 官方源码; CMakeLists 删除 5.1 不存在的
  lcorolib.c/lctype.c/lutf8lib.c/lbitlib.c
- 补充 lua.hpp C++ 包装头(5.1 官方不提供, 保持桥接 include 路径不变)
- LUA_OK 兼容宏: 5.1 无此定义(成功返回值为 0)
- luaL_tolstring 兼容: 5.1 无此 API, l_print 改用 lua_tostring +
  lua_typename 兜底(#if LUA_VERSION_NUM >= 502 条件编译, 弹栈逻辑同步分支)
- luaL_setfuncs 兼容: 5.1 无此 API, push_tty_file 改手动循环注册
- I/O 重定向沿用 Registry 方案(自 5.2.4 分支同步), typed interop
  版本自适应断言同步
- 验证: GTest 44/44 通过

lib/lua/lzio.h

@@ -1,5 +1,5 @@
 /*
-** $Id: lzio.h $
+** $Id: lzio.h,v 1.21.1.1 2007/12/27 13:02:25 roberto Exp $
 ** Buffered streams
 ** See Copyright Notice in lua.h
 */
@@ -17,8 +17,9 @@
 
 typedef struct Zio ZIO;
 
-#define zgetc(z)  (((z)->n--)>0 ?  cast_uchar(*(z)->p++) : luaZ_fill(z))
+#define char2int(c)	cast(int, cast(unsigned char, (c)))
 
+#define zgetc(z)  (((z)->n--)>0 ?  char2int(*(z)->p++) : luaZ_fill(z))
 
 typedef struct Mbuffer {
   char *buffer;
@@ -32,21 +33,21 @@ 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 */
+LUAI_FUNC int luaZ_lookahead (ZIO *z);
 
 
 
@@ -55,8 +56,8 @@ LUAI_FUNC size_t luaZ_read (ZIO* z, void *b, size_t n);	/* read next n bytes */
 struct Zio {
   size_t n;			/* bytes still unread */
   const char *p;		/* current position in buffer */
-  lua_Reader reader;		/* reader function */
-  void *data;			/* additional data */
+  lua_Reader reader;
+  void* data;			/* additional data */
   lua_State *L;			/* Lua state (for reader) */
 };