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/cache.c b/src/cache.c
index fdb0f25..9b77121 100644
--- a/src/cache.c
+++ b/src/cache.c
@@ -617,7 +617,7 @@
 			offset = 0;
 		if (ret <= 0) {
 			if (ret == -3 || ret == -1) {
-				si_cant_put(si);
+				si_rx_room_blk(si);
 				break;
 			}
 			return -1;
@@ -1142,7 +1142,7 @@
 		if (!next_key) {
 			chunk_printf(&trash, "%p: %s (shctx:%p, available blocks:%d)\n", cache, cache->id, shctx_ptr(cache), shctx_ptr(cache)->nbav);
 			if (ci_putchk(si_ic(si), &trash) == -1) {
-				si_cant_put(si);
+				si_rx_room_blk(si);
 				return 0;
 			}
 		}
@@ -1168,7 +1168,7 @@
 			shctx_unlock(shctx_ptr(cache));
 
 			if (ci_putchk(si_ic(si), &trash) == -1) {
-				si_cant_put(si);
+				si_rx_room_blk(si);
 				return 0;
 			}
 		}