[Perl/perl5] dab400: fix "equivelent" in a few places

[Tony Cook via perl5-changes]

  Branch: refs/heads/blead
  Home:   https://github.com/Perl/perl5
  Commit: dab4006c92d70a54e7909d0e670b71bfd3fb8221
      
https://github.com/Perl/perl5/commit/dab4006c92d70a54e7909d0e670b71bfd3fb8221
  Author: Tony Cook <t...@develop-help.com>
  Date:   2023-02-21 (Tue, 21 Feb 2023)

  Changed paths:
    M lib/perl5db.t

  Log Message:
  -----------
  fix "equivelent" in a few places

Be a bit clearer that this is used for testing perl itself.