cligen: update git submodule

To avoid emitting empty "list" substruct in header files, as well as
assuming the Python pwd module is always available.

Signed-off-by: Daiki Ueno <ueno@gnu.org>

diff --git a/devel/cligen b/devel/cligen
index 8b12ee6f36349f9f39d5a244347ba616116d6214..3e3af3f4da242fec3588a28592f48925d730fbee 160000 (submodule)
--- a/devel/cligen
+++ b/devel/cligen
@@ -1 +1 @@
-Subproject commit 8b12ee6f36349f9f39d5a244347ba616116d6214
+Subproject commit 3e3af3f4da242fec3588a28592f48925d730fbee