Generate lc_def_codeset.h header containing the default mapping from
locale to codeset on Linux. Use this mapping in __set_charset_from_locale
in the first place.
For every locale not covered by this table, just map Windows codepages
to equivalent codesets used on Linux/Unix, getting rid of LCIDs entirely.
Signed-off-by: Corinna Vinschen <corinna@vinschen.de>