build: do not remove definition of ENODATA, after all

* src/system.h (ENODATA): Restore definition.
gnulib defines it only on native Windows systems, so removing our
definition would have provoked build failure on systems that use it,
like FreeBSD.  Reported by Bruno Haible in
http://thread.gmane.org/gmane.comp.lib.gnulib.bugs/28739/focus=28795
* gnulib: Update to latest, to get new ENODATA-exempting maint.mk rule.

1 files changed, 0 insertions, 0 deletions

diff --git a/gnulib b/gnulib
-Subproject 71f13422f3e6345933513607255f1f7a7526e93
+Subproject f1a5c91522554791317dc2ee763fe8c017c7b81