So far locale(1) had to have knowledge how to construct, thus
duplicating the effort how Cygwin handles locale strings.
Move locale list and codeset list generation into Cygwin by
providing /proc/codesets and /proc/locales files. /proc/locales
does not list aliases, those are still handled in locale(1).
locale(1) opens the files and ueses that info for printing,
like any other application can do now.
Signed-off-by: Corinna Vinschen <corinna@vinschen.de>