Update after gnulib changed.
* gettext-runtime/m4/intl.m4 (AM_INTL_SUBDIR): Test
gt_localename_enhances_locale_funcs instead of gt_nameless_locales. Set
ENHANCE_LOCALE_FUNCS, not HAVE_NAMELESS_LOCALES.
* gettext-runtime/intl/Makefile.am (libgnuintl.h, libintl.h): Substitute
ENHANCE_LOCALE_FUNCS, not HAVE_NAMELESS_LOCALES.
* gettext-runtime/intl/libgnuintl.in.h: Test ENHANCE_LOCALE_FUNCS, not
HAVE_NAMELESS_LOCALES.
* gettext-runtime/intl/localename.c: Update from gnulib.
* gettext-runtime/m4/iconv.m4: Likewise.
