CLEANUP: listeners: remove unreachable code in clone_listener()

Coverity reported in issue #1416 that label oom3 is not reachable in
function close_listener() added by commit 59a877dfd ("MINOR: listeners:
add clone_listener() to duplicate listeners at boot time"). The code
leading to it was removed during the development of the function, but
not the label itself.
diff --git a/src/listener.c b/src/listener.c
index 5c2eb21..c4be8dd 100644
--- a/src/listener.c
+++ b/src/listener.c
@@ -704,8 +704,6 @@
 	global.maxsock++;
 	return l;
 
- oom3:
-	free(l->name);
  oom2:
 	free(l);
  oom1: