Cygwin 2.6 introduced uselocale() and thread-local locales in general,
but lacks any way to get at the name of each portion of a locale_t
object short of peeking behind an opaque object. Cygwin has just
been patched to add NL_LOCALE_NAME() patterned after glibc's
extension of the same name[1], but as that version of Cygwin has not
yet been released, we might as well work around it in the meantime.
* lib/localename.c (gl_locale_name_thread_unsafe): Add clause for
Cygwin.
* modules/localename (Depends-on): Add extensions, since
NL_LOCALE_NAME() is not visible without it.