There's a closed pull request on the void-packages repository

mpv: add sndio patch
https://github.com/void-linux/void-packages/pull/34671

Description:
<!-- Uncomment relevant sections and delete options which are not applicable -->

#### Testing the changes
- I tested the changes in this PR: **YES**

lifted from the following without modification:
- http://cvsweb.openbsd.org/cgi-bin/cvsweb/ports/multimedia/mpv/patches/patch-audio_out_ao_c?rev=1.3&content-type=text/x-cvsweb-markup
- http://cvsweb.openbsd.org/cgi-bin/cvsweb/ports/multimedia/mpv/patches/patch-audio_out_ao_sndio_c?rev=1.4&content-type=text/x-cvsweb-markup
- http://cvsweb.openbsd.org/cgi-bin/cvsweb/ports/multimedia/mpv/patches/patch-wscript?rev=1.5&content-type=text/x-cvsweb-markup
- http://cvsweb.openbsd.org/cgi-bin/cvsweb/ports/multimedia/mpv/patches/patch-wscript_build_py?rev=1.3&content-type=text/x-cvsweb-markup

thanks brad