[Perl/perl5] b1a94f: perl.h: Turn mutex warning into a panic

[Karl Williamson via perl5-changes]

  Branch: refs/heads/blead
  Home:   https://github.com/Perl/perl5
  Commit: b1a94fceb233fe356552304fa097b86510668cbd
      
https://github.com/Perl/perl5/commit/b1a94fceb233fe356552304fa097b86510668cbd
  Author: Karl Williamson <k...@cpan.org>
  Date:   2023-09-28 (Thu, 28 Sep 2023)

  Changed paths:
    M perl.h

  Log Message:
  -----------
  perl.h: Turn mutex warning into a panic

This was my attempt to keep going and try to recover after a problem was
found:  an unbalanced number of  locks/unlocks.  However, in looking at
a many-million line execution trace, I realized that the recovery likely
doesn't lead to correct results, and we should quit immediately should
it happen.