BUG/MINOR: cli: correctly handle abns in 'show cli sockets'

The 'show cli sockets' was not handling the abns sockets. This is a
problem since it uses the AF_UNIX family, it displays nothing
in the path column because the path starts by \0.

Should be backported to 1.9 and 1.8.
diff --git a/src/cli.c b/src/cli.c
index 38c178d..2527e89 100644
--- a/src/cli.c
+++ b/src/cli.c
@@ -1078,7 +1078,10 @@
 							const struct sockaddr_un *un;
 
 							un = (struct sockaddr_un *)&l->addr;
-							chunk_appendf(&trash, "%s ", un->sun_path);
+							if (un->sun_path[0] == '\0')
+								chunk_appendf(&trash, "abns@%s ", un->sun_path+1);
+							else
+								chunk_appendf(&trash, "%s ", un->sun_path);
 						} else if (l->addr.ss_family == AF_INET) {
 							addr_to_str(&l->addr, addr, sizeof(addr));
 							port_to_str(&l->addr, port, sizeof(port));