DEV: flags: add missing CO_FL_FDLESS connection flag

This was added in 2.6 by commit c78a9698e ("MINOR: connection: add a new
flag CO_FL_FDLESS on fd-less connections") but forgotten in flags.c.
This must be backported to 2.6.
diff --git a/dev/flags/flags.c b/dev/flags/flags.c
index 711f451..de7127d 100644
--- a/dev/flags/flags.c
+++ b/dev/flags/flags.c
@@ -156,6 +156,7 @@
 	SHOW_FLAG(f, CO_FL_SEND_PROXY);
 	SHOW_FLAG(f, CO_FL_WAIT_L6_CONN);
 	SHOW_FLAG(f, CO_FL_WAIT_L4_CONN);
+	SHOW_FLAG(f, CO_FL_FDLESS);
 	SHOW_FLAG(f, CO_FL_ERROR);
 	SHOW_FLAG(f, CO_FL_SOCK_WR_SH);
 	SHOW_FLAG(f, CO_FL_SOCK_RD_SH);