MINOR: cli: parse prompt command in the CLI proxy

Handle the prompt command. Works the same way as the CLI.
diff --git a/include/types/stream.h b/include/types/stream.h
index 87bdf46..52c0b97 100644
--- a/include/types/stream.h
+++ b/include/types/stream.h
@@ -163,6 +163,8 @@
 			  struct stream_interface *si);
 
 	int pcli_next_pid;                      /* next target PID to use for the CLI proxy */
+	int pcli_prompt;                        /* is there a prompt ?! */
+
 	char *unique_id;                        /* custom unique ID */
 
 	/* These two pointers are used to resume the execution of the rule lists. */
diff --git a/src/cli.c b/src/cli.c
index e7682f5..3171c0a 100644
--- a/src/cli.c
+++ b/src/cli.c
@@ -1657,6 +1657,9 @@
 	struct buffer *msg = get_trash_chunk();
 	struct channel *oc = si_oc(&s->si[0]);
 
+	if (!s->pcli_prompt)
+		return;
+
 	if (s->pcli_next_pid == 0)
 		chunk_appendf(msg, "master> ");
 	else
@@ -1781,6 +1784,9 @@
 		else
 			*next_pid = target_pid;
 		return 1;
+	} else if (!strcmp("prompt", args[0])) {
+		s->pcli_prompt ^= 1;
+		return argl; /* return the number of elements in the array */
 	}
 
 	return 0;
diff --git a/src/stream.c b/src/stream.c
index 805fe4d..67b0c8d 100644
--- a/src/stream.c
+++ b/src/stream.c
@@ -201,6 +201,7 @@
 
 	s->flags |= SF_INITIALIZED;
 	s->pcli_next_pid = 0;
+	s->pcli_prompt = 0;
 	s->unique_id = NULL;
 
 	if ((t = task_new(tid_bit)) == NULL)