Update libucl.

diff --git a/src/ucl b/src/ucl
index f918967acb044eb79d9957278dfcb88e45eb130a..a50b18f7fe74bd4bfa4a73dd7b8f325824ff031b 160000 (submodule)
--- a/src/ucl
+++ b/src/ucl
@@ -1 +1 @@
-Subproject commit f918967acb044eb79d9957278dfcb88e45eb130a
+Subproject commit a50b18f7fe74bd4bfa4a73dd7b8f325824ff031b