build: update gnulib submodule to newer (but not latest)

This is a stop-gap measure to make autogen.sh rerun ./bootstrap,
(required due to recent bootstrap.conf addition) while we prepare
the fix to automatically detect the case of an updated modules list.

.gnulib @ 10d66aed

-Subproject commit 80cd995cdcbf4b9ded895a43621a11f11806ad8d
+Subproject commit 10d66aedfdd610f731c8c54152b9dfca3efbee12