build: update gnulib, for syntax-check vs canonicalize fix

diff --git a/gnulib b/gnulib
index 4994b1aab88924f5db960472c2189fa1b46c6778..bfb5863e350590d8fe9a643d840c7d0b5f3d934b 160000 (submodule)
--- a/gnulib
+++ b/gnulib
@@ -1 +1 @@
-Subproject commit 4994b1aab88924f5db960472c2189fa1b46c6778
+Subproject commit bfb5863e350590d8fe9a643d840c7d0b5f3d934b