Fix. Cleanup socket callback.

Author: moteus

src/lcmulti.c

@@ -74,7 +74,10 @@ static int lcurl_multi_cleanup(lua_State *L){
 
   luaL_unref(L, LCURL_LUA_REGISTRY, p->tm.cb_ref);
   luaL_unref(L, LCURL_LUA_REGISTRY, p->tm.ud_ref);
+  luaL_unref(L, LCURL_LUA_REGISTRY, p->sc.cb_ref);
+  luaL_unref(L, LCURL_LUA_REGISTRY, p->sc.ud_ref);
   p->tm.cb_ref = p->tm.ud_ref = LUA_NOREF;
+  p->sc.cb_ref = p->sc.ud_ref = LUA_NOREF;
   return 0;
 }