pulse: handle wraparound near the end correctly

If offset is near MAXLENGTH, we can read past the end of the
buffer. Use the ringbuffer API to correctly wraparound.

src/modules/module-protocol-pulse/sample-play.c

@@ -100,7 +100,8 @@ static void sample_play_stream_process(void *data)
 	if (b->requested)
 		size = SPA_MIN(size, b->requested * p->stride);
 
-	memcpy(d, s->buffer + p->offset, size);
+	spa_ringbuffer_read_data(NULL, s->buffer, MAXLENGTH,
+			p->offset % MAXLENGTH, d, size);
 
 	p->offset += size;