build: update gnulib to latest

diff --git a/gnulib b/gnulib
index b392a22453f992de59b63b157c191d3118fb9ed7..87f692bf1126a16c40212bcdb5324625939cef2a 160000 (submodule)
--- a/gnulib
+++ b/gnulib
@@ -1 +1 @@
-Subproject commit b392a22453f992de59b63b157c191d3118fb9ed7
+Subproject commit 87f692bf1126a16c40212bcdb5324625939cef2a