[Perl/perl5] fb5889: Document suggestion to use libffi for simple libra...

[Dan Book]

  Branch: refs/heads/blead
  Home:   https://github.com/Perl/perl5
  Commit: fb588969f8e166671b5c0281db1fd896400d8f6d
      
https://github.com/Perl/perl5/commit/fb588969f8e166671b5c0281db1fd896400d8f6d
  Author: Dan Book <gri...@grinnz.com>
  Date:   2020-01-09 (Thu, 09 Jan 2020)

  Changed paths:
    M dist/ExtUtils-ParseXS/lib/perlxs.pod
    M t/porting/known_pod_issues.dat

  Log Message:
  -----------
  Document suggestion to use libffi for simple library bindings