Instead of relying on the iso-codes package, use the native Windows NLS APIs to
acquire the localized (translated) language names so that we do not need to
incur an extra runtime dependency on Windows. It's not coverering 100% of the
languages that we would like to support through this, but should cover much of
the things that are required.
Remove g_auto*() usage from these sources and use the traditional
g_free(), as g_auto*() are GCCisms (or CLangisms).
Also, don't include unistd.h unconditionally and stop including
langinfo.h and dirent.h, since they seem to be unused.
https://bugzilla.gnome.org/show_bug.cgi?id=773299
