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/flt_spoe.c b/src/flt_spoe.c
index edb853a..72e1773 100644
--- a/src/flt_spoe.c
+++ b/src/flt_spoe.c
@@ -1156,7 +1156,7 @@
 	ret = ci_putblk(si_ic(si), buf, framesz+4);
 	if (ret <= 0) {
 		if ((ret == -3 && b_is_null(&si_ic(si)->buf)) || ret == -1) {
-			si_cant_put(si);
+			si_rx_room_blk(si);
 			return 1; /* retry */
 		}
 		SPOE_APPCTX(appctx)->status_code = SPOE_FRM_ERR_IO;