localcharset: Clean up locale encodings used by glibc

[Bruno Haible]

This patch removes from lib/localcharset.h some of those encodings that are
not supported by glibc for more than 10 years.


2023-07-13  Bruno Haible  <bruno@clisp.org>

        localcharset: Clean up locale encodings used by glibc.
        * lib/localcharset.h: Remove VISCII from the list, since never supported
        in glibc/localedata/SUPPORTED. JOHAB is not supported by glibc any more
        since 2000-09-25. TCVN5712-1 is not supported by glibc any more since
        2012-05-21.

diff --git a/lib/localcharset.h b/lib/localcharset.h
index 29ee8dc04b..25c9bb9c6e 100644
--- a/lib/localcharset.h
+++ b/lib/localcharset.h
@@ -104,10 +104,8 @@ extern const char * locale_charset (void);
    GBK                         glibc aix osf solaris freebsd darwin cygwin 
windows dos
    GB18030                     glibc hpux solaris freebsd netbsd darwin
    SHIFT_JIS               Y   hpux osf solaris freebsd netbsd darwin
-   JOHAB                       glibc solaris windows
+   JOHAB                       solaris windows
    TIS-620                     glibc aix hpux osf solaris cygwin zos
-   VISCII                  Y   glibc
-   TCVN5712-1                  glibc
    ARMSCII-8                   glibc freebsd netbsd darwin
    GEORGIAN-PS                 glibc cygwin
    PT154                       glibc netbsd cygwin