audio/pipewire-spa-oss-ng: Update to 0.9.4

Capture (source) fixes for cramped rings and fat strides

Fixes a field report of skipping audio when recording and playing back
at once on a fat-stride USB capture device (20-channel S32, 80
bytes/frame): FreeBSD clamps the soft ring at CHN_2NDBUFMAXSIZE, so it
holds only ~1.6 graph periods there, and the capture path had no
headroom for arrival jitter.