BUG/MEDIUM: h1: Set CS_FL_REOS if we had a read0.

In h1_recv(), if we get a read0, let the conn_stream know by setting the
CS_FL_REOS flag, or it may never be aware we did hit EOS.

This should not be backported.
diff --git a/src/mux_h1.c b/src/mux_h1.c
index c329340..c2d0030 100644
--- a/src/mux_h1.c
+++ b/src/mux_h1.c
@@ -1587,6 +1587,8 @@
 		h1s->recv_wait = NULL;
 
 	}
+	if (conn_xprt_read0_pending(conn))
+		h1s->cs->flags |= CS_FL_REOS;
 	if (!b_data(&h1c->ibuf))
 		h1_release_buf(h1c, &h1c->ibuf);
 	else if (!buf_room_for_htx_data(&h1c->ibuf))