build: update gnulib submodule to latest

diff --git a/gnulib b/gnulib
index 98aa8776dd2b510b7f777870fb76b17fd88abbef..fa214897526d2822e88175fd840cf08ca3e6ba81 160000 (submodule)
--- a/gnulib
+++ b/gnulib
@@ -1 +1 @@
-Subproject commit 98aa8776dd2b510b7f777870fb76b17fd88abbef
+Subproject commit fa214897526d2822e88175fd840cf08ca3e6ba81