add mongo auth support, and copy a md5 lib to 3rd

3rd/lua-md5/compat-5.2.c

@@ -0,0 +1,21 @@
+#include "lua.h"
+#include "lauxlib.h"
+#include "compat-5.2.h"
+
+#if !defined LUA_VERSION_NUM || LUA_VERSION_NUM==501
+/*
+** Adapted from Lua 5.2.0
+*/
+void luaL_setfuncs (lua_State *L, const luaL_Reg *l, int nup) {
+  luaL_checkstack(L, nup+1, "too many upvalues");
+  for (; l->name != NULL; l++) {  /* fill the table with given functions */
+    int i;
+    lua_pushstring(L, l->name);
+    for (i = 0; i < nup; i++)  /* copy upvalues to the top */
+      lua_pushvalue(L, -(nup + 1));
+    lua_pushcclosure(L, l->func, nup);  /* closure with those upvalues */
+    lua_settable(L, -(nup + 3)); /* table must be below the upvalues, the name and the closure */
+  }
+  lua_pop(L, nup);  /* remove upvalues */
+}
+#endif