[Perl/perl5] fc10a7: improve comments about XORSHIFT macros

[Yves Orton via perl5-changes]

  Branch: refs/heads/yves/consistent_srand
  Home:   https://github.com/Perl/perl5
  Commit: fc10a7da4fd28e60fd52d92d4c3d816928b67e33
      
https://github.com/Perl/perl5/commit/fc10a7da4fd28e60fd52d92d4c3d816928b67e33
  Author: Yves Orton <demer...@gmail.com>
  Date:   2022-08-10 (Wed, 10 Aug 2022)

  Changed paths:
    M handy.h

  Log Message:
  -----------
  improve comments about XORSHIFT macros