[Perl/perl5] 26d1d7: Document and consolidate SvPV..force functions

[Karl Williamson via perl5-changes]

  Branch: refs/heads/blead
  Home:   https://github.com/Perl/perl5
  Commit: 26d1d7c7534e64e87310befc9919ef4779943bd6
      
https://github.com/Perl/perl5/commit/26d1d7c7534e64e87310befc9919ef4779943bd6
  Author: Karl Williamson <k...@cpan.org>
  Date:   2020-12-13 (Sun, 13 Dec 2020)

  Changed paths:
    M sv.h

  Log Message:
  -----------
  Document and consolidate SvPV..force functions