audio/openal-soft: Include the last patch for upstream sndio backend.

Details:

• Backport the remaining sndio backend commit at: https://github.com/kcat/openal-soft/commit/2df78e49b1359e7603e3816270737c68cccd5b05

Reported by: Brad Smith <brad@comstyle.com>
MFH: 2021Q4

(cherry picked from commit 520be1663a38864dc78882d186d423ba900a46ad)