vendor: 引入 Lua 2.5 官方源码 + 移植评估 (lua_2.5 分支)

- 前 lua_State 时代 API, 比 3.2 更原始(无 upvalue/无独立编译)
- 评估结论: 不建议移植(多实例冲突+管道模式不可实现), 见 doc/ADAPTATION-lua25.md
- 建议历史脚本用 5.1 兼容模式运行替代

lib/lua/src/mem.c

@@ -0,0 +1,58 @@
+/*
+** mem.c
+** TecCGraf - PUC-Rio
+*/
+
+char *rcs_mem = "$Id: mem.c,v 1.13 1996/05/24 14:31:10 roberto Exp $";
+
+#include <stdlib.h>
+
+#include "mem.h"
+#include "lua.h"
+
+
+void luaI_free (void *block)
+{
+  if (block)
+  {
+    *((int *)block) = -1;  /* to catch errors */
+    free(block);
+  }
+}
+
+
+void *luaI_realloc (void *oldblock, unsigned long size)
+{
+  void *block;
+  size_t s = (size_t)size;
+  if (s != size)
+    lua_error("Allocation Error: Block too big");
+  block = oldblock ? realloc(oldblock, s) : malloc(s);
+  if (block == NULL)
+    lua_error(memEM);
+  return block;
+}
+
+
+int luaI_growvector (void **block, unsigned long nelems, int size,
+                       char *errormsg, unsigned long limit)
+{
+  if (nelems >= limit)
+    lua_error(errormsg);
+  nelems = (nelems == 0) ? 20 : nelems*2;
+  if (nelems > limit)
+    nelems = limit;
+  *block = luaI_realloc(*block, nelems*size);
+  return (int)nelems;
+}
+
+
+void* luaI_buffer (unsigned long size)
+{
+  static unsigned long buffsize = 0;
+  static char* buffer = NULL;
+  if (size > buffsize)
+    buffer = luaI_realloc(buffer, buffsize=size);
+  return buffer;
+}
+