build: update gnulib submodule to latest

diff --git a/gnulib b/gnulib
index 3c893dc1b075bc874c325f0dea0cd0bcb46715c1..af32ee824ee18255839f9812b8ed61aa5257a82b 160000 (submodule)
--- a/gnulib
+++ b/gnulib
@@ -1 +1 @@
-Subproject commit 3c893dc1b075bc874c325f0dea0cd0bcb46715c1
+Subproject commit af32ee824ee18255839f9812b8ed61aa5257a82b