MINOR: conn-stream: Force mux to wait for read events if abortonclose is set

When the abortonclose option is enabled, to be sure to be immediately
notified when a shutdown is received from the client, the frontend
conn-stream must be sure the mux will wait for read events. To do so, the
CO_RFL_KEEP_RECV flag is set when mux->rcv_buf() is called. This new flag
instructs the mux to wait for read events, regardless its internal state.

This patch is required to fix abortonclose option for H1 client connections.

(cherry picked from commit d8219b31e7cfe0dec64c33e1186e5f33cf87191a)
Signed-off-by: Christopher Faulet <cfaulet@haproxy.com>
diff --git a/include/haproxy/connection-t.h b/include/haproxy/connection-t.h
index 4c460a3..401d756 100644
--- a/include/haproxy/connection-t.h
+++ b/include/haproxy/connection-t.h
@@ -270,6 +270,7 @@
 	CO_RFL_BUF_WET     = 0x0001,    /* Buffer still has some output data present */
 	CO_RFL_BUF_FLUSH   = 0x0002,    /* Flush mux's buffers but don't read more data */
 	CO_RFL_READ_ONCE   = 0x0004,    /* don't loop even if the request/response is small */
+	CO_RFL_KEEP_RECV   = 0x0008,    /* Instruct the mux to still wait for read events  */
 };
 
 /* flags that can be passed to xprt->snd_buf() and mux->snd_buf() */
diff --git a/src/stream_interface.c b/src/stream_interface.c
index ffd8f8e..47c36d9 100644
--- a/src/stream_interface.c
+++ b/src/stream_interface.c
@@ -1341,6 +1341,7 @@
 		 * CS_FL_RCV_MORE on the CS if more space is needed.
 		 */
 		max = channel_recv_max(ic);
+		flags |= ((!conn_is_back(conn) && (si_strm(si)->be->options & PR_O_ABRT_CLOSE)) ? CO_RFL_KEEP_RECV : 0);
 		ret = cs->conn->mux->rcv_buf(cs, &ic->buf, max, flags | (co_data(ic) ? CO_RFL_BUF_WET : 0));
 
 		if (cs->flags & CS_FL_WANT_ROOM)