maint: update to latest gnulib

Required for the copyright year bump to keep 'make syntax-check'
happy, and also pulls in several portability fixes.

* .gnulib: Update to latest.
* bootstrap: Resync from upstream.
Signed-off-by: NMichal Privoznik <mprivozn@redhat.com>

.gnulib @ e210a3cb

-Subproject commit c3b131294aa42b7997cc9b9a0bbb2934aa27fd6c
+Subproject commit e210a3cbaec0ee82a67ff8fc427e21bdd64dba1b