[Perl/perl5] 7f3402: locale.c: handle codesets GB18030, EUC-TW

[Karl Williamson via perl5-changes]

  Branch: refs/heads/blead
  Home:   https://github.com/Perl/perl5
  Commit: 7f3402777ae7541fe5b0ade7791871742645f5ea
      
https://github.com/Perl/perl5/commit/7f3402777ae7541fe5b0ade7791871742645f5ea
  Author: Karl Williamson <k...@cpan.org>
  Date:   2024-01-02 (Tue, 02 Jan 2024)

  Changed paths:
    M locale.c

  Log Message:
  -----------
  locale.c: handle codesets GB18030, EUC-TW

These two codesets are multi-byte, like UTF-8.  Previously we sort of-of
looked for them, but not fully.  This commit rectifies that.  If the
code set matches one of those two, we don't create a bias towards the
locale being UTF-8.

I discovered this by testing in an unusual Configuration.