Measure call audio processing and send queue residence

src/call/call_priv.h

@@ -22,6 +22,8 @@ struct call_session {
     struct ll_queue *tx_q;
     struct queue_waiter_handle send_waiter;
     uint32_t c_tx_frames, c_rx_frames, c_tx_dropped, c_rx_dropped;
+    uint64_t tx_wait_total_ms;
+    uint32_t tx_wait_frames, tx_wait_max_ms;
     struct call_video_transport *video;
 };
 struct call_ctx {