build: update gnulib submodule to latest

diff --git a/gnulib b/gnulib
index da6b90f1fd041c013b9685ec4256e16d75b83f5d..c08abe38ebc2cfd8e0901230f48374d632e95868 160000 (submodule)
--- a/gnulib
+++ b/gnulib
@@ -1 +1 @@
-Subproject commit da6b90f1fd041c013b9685ec4256e16d75b83f5d
+Subproject commit c08abe38ebc2cfd8e0901230f48374d632e95868