pulse-server: stream: remove done flag

When the `done` flag was first added in
9f9be7d7f2, it was
actually needed because cleanup was implemented
using a per-client eventfd which was signalled when
something related to the particular client needed
to be freed. The function that ran, then, checked
each stream's `done` flag, and freed them as necessary.

However, since c70a5de526,
the stream cleanup is done using a work queue, and as
a consequence, the `done` flag is no longer needed.

src/modules/module-protocol-pulse/stream.h

@@ -111,7 +111,6 @@ struct stream {
 	unsigned int adjust_latency:1;
 	unsigned int is_underrun:1;
 	unsigned int in_prebuf:1;
-	unsigned int done:1;
 	unsigned int killed:1;
 	unsigned int pending:1;
 };