[Perl/perl5] 7c60f1: Implement builtin::stringify

[Paul Evans via perl5-changes]

  Branch: refs/heads/blead
  Home:   https://github.com/Perl/perl5
  Commit: 7c60f1f796a4c23bbfc43b25f2e159ffea14300b
      
https://github.com/Perl/perl5/commit/7c60f1f796a4c23bbfc43b25f2e159ffea14300b
  Author: Paul "LeoNerd" Evans <leon...@leonerd.org.uk>
  Date:   2023-09-08 (Fri, 08 Sep 2023)

  Changed paths:
    M builtin.c
    M lib/builtin.pm
    M lib/builtin.t

  Log Message:
  -----------
  Implement builtin::stringify