build: update gnulib submodule to latest

diff --git a/gnulib b/gnulib
index 30fcbcc4db4973f84999a00c30e490e39989e96e..66d32ceddd565abff57901c59014023a9426cc8a 160000 (submodule)
--- a/gnulib
+++ b/gnulib
@@ -1 +1 @@
-Subproject commit 30fcbcc4db4973f84999a00c30e490e39989e96e
+Subproject commit 66d32ceddd565abff57901c59014023a9426cc8a