How to set ALSA option for multimedia/mpv on 14current.

From: Masachika ISHIZUKA <ish_at_amail.plala.or.jp>
Date: Wed, 15 Dec 2021 03:26:30 UTC
  Hi.

  I want to enable ALSA for multimedia/mpv.
  As mpv is paused every movies with oss driver, I want to enable
ALSA option to privent this.

% cd /usr/ports/multimedia/mpv
% make rmconfig
===> No user-specified options configured for mpv-0.34.0_2,1
% make config
===>  Switching to root credentials to create /var/db/ports/multimedia_mpv
Password:
===>  Returning to user credentials
===> Options unchanged
% uname -UK
1400043 1400043
% uname -a
FreeBSD carrot.ish.org 14.0-CURRENT FreeBSD 14.0-CURRENT #17 master-n251309-fc21aafe5ff-dirty: Sat Dec  4 15:24:39 JST 2021     ishizuka@okra.ish.org:/usr/obj/usr/src/amd64.amd64/sys/SG_UDF2  amd64

  I can't change options for multimedia/mpv on recent 14-current.
-- 
Masachika ISHIZUKA