MINOR: stream-int: replace si_cant_put() with si_rx_room_{blk,rdy}()

Remaining calls to si_cant_put() were all for lack of room and were
turned to si_rx_room_blk(). A few places where SI_FL_RXBLK_ROOM was
cleared by hand were converted to si_rx_room_rdy().

The now unused si_cant_put() function was removed.
diff --git a/src/peers.c b/src/peers.c
index 649af83..76ecf68 100644
--- a/src/peers.c
+++ b/src/peers.c
@@ -1892,7 +1892,7 @@
 		HA_SPIN_UNLOCK(PEER_LOCK, &curpeer->lock);
 	return;
 full:
-	si_cant_put(si);
+	si_rx_room_blk(si);
 	goto out;
 }