build: update gnulib submodule to latest

diff --git a/gnulib b/gnulib
index 62e51f9..2b2bcdb 160000 (submodule)
--- a/gnulib
+++ b/gnulib
@@ -1 +1 @@
-Subproject commit 62e51f91499a7844a9de9ee7553a79a93c80ce37
+Subproject commit 2b2bcdbc3bf3de2838a4b5051e32366e9a94f1e3