Adjust to yesterday’s Gnulib nstrftime changes

Adjust to yesterday’s Gnulib nstrftime changes

Bruno Haible fixed Gnulib so that nstrftime no longer requires
locking code, which means we no longer need to avoid localename.
However, nstrftime now requires localename-unsafe-limited which
pulls in some Gnulib-specific locale code, and it’s likely this
needs to be replaced with Emacs-specific locale code.  In the
meantime let’s continue to finess this by avoiding
localename-unsafe-limited.
* admin/merge-gnulib (AVOIDED_MODULES):
Avoid localename-unsafe-limited instead of localename.