alsa: add dll to estimate clock drift

Make delay signed in the clock io so that we can simply add it to the
tick to get the hw position.
Add clock drift to clock info

src/pipewire/stream.h

@@ -324,13 +324,13 @@ struct pw_time {
 	int64_t now;			/**< the monotonic time */
 	struct spa_fraction rate;	/**< the rate of \a ticks and delay */
 	uint64_t ticks;			/**< the ticks at \a now. This is the current time that
-					     the remote end is reading/writing. */
-	uint64_t delay;			/**< delay to device, add to ticks for INPUT streams and
-					     subtract from ticks for OUTPUT streams to get the
-					     time of the device. */
+					  *  the remote end is reading/writing. */
+	int64_t delay;			/**< delay to device, add to ticks to get the time of the
+					  *  device. Positive for INPUT streams and
+					  *  negative for OUTPUT streams. */
 	uint64_t queued;		/**< data queued in the stream, this is the sum
-					     of the size fields in the pw_buffer that are
-					     currently queued */
+					  *  of the size fields in the pw_buffer that are
+					  *  currently queued */
 };
 /** Query the time on the stream \memberof pw_stream */
 int pw_stream_get_time(struct pw_stream *stream, struct pw_time *time);