maint: translate messages from Gnulib

Problem reported by ribbon in:
https://lists.gnu.org/r/coreutils/2026-08/msg00093.html
* configure.ac (GNULIB_TEXT_DOMAIN): Define.
* po/POTFILES.in: Add lib/parse-datetime.y.

NEWS

@@ -80,6 +80,9 @@ GNU coreutils NEWS                                    -*- outline -*-
   locales like SHIFT-JIS where a single byte can decode to a wide character.
   [bug introduced in coreutils-9.5]
 
+  Messages from Gnulib are no longer mistranslated in non-English locales.
+  [bug introduced in coreutils-9.6]
+
 ** New Features
 
   'env' now supports --env0-from=FILE to read NUL-delimited environment entries

configure.ac

@@ -63,6 +63,10 @@ gl_SET_CRYPTO_CHECK_DEFAULT([auto-gpl-compat])
 gl_INIT
 coreutils_MACROS
 
+# Translate Gnulib msgids ourselves, instead of using the gnulib-l10n module.
+AC_DEFINE([GNULIB_TEXT_DOMAIN], [PACKAGE],
+  [The text domainname for Gnulib messages.])
+
 # These are safe, since 'sort', coreutils's only multithreaded app,
 # does not use the relevant modules, or calls their code from one thread.
 AC_DEFINE([GNULIB_EXCLUDE_SINGLE_THREAD], [1],

po/POTFILES.in

@@ -14,6 +14,7 @@ lib/getopt.c
 lib/mkdir-p.c
 lib/obstack.c
 lib/openat-die.c
+lib/parse-datetime.y
 lib/quotearg.c
 lib/randread.c
 lib/regcomp.c