Add underscore.

Both cfg and cfg_ refer to the same thing, which is why it works anyway, but it's still a typo.

src/server/wesnothd/player.cpp

@@ -34,7 +34,7 @@ wesnothd::player::player(const std::string& n, simple_wml::node& cfg, int id,
 	cfg_.set_attr_dup("name", n.c_str());
 	cfg_.set_attr("registered", registered ? "yes" : "no");
 	cfg_.set_attr("moderator", moderator ? "yes" : "no");
-	cfg.set_attr_int("forum_id", id);
+	cfg_.set_attr_int("forum_id", id);
 	mark_available();
 }