[Perl/perl5] f5c3fe: GH #18163: Stricter, cleaned up test example:

[Sawyer X via perl5-changes]

  Branch: refs/heads/docs/strict-xstut-test
  Home:   https://github.com/Perl/perl5
  Commit: f5c3fe5da9d0e1dab695abe8baf2b7dab05c856d
      
https://github.com/Perl/perl5/commit/f5c3fe5da9d0e1dab695abe8baf2b7dab05c856d
  Author: Sawyer X <xsawy...@cpan.org>
  Date:   2020-09-25 (Fri, 25 Sep 2020)

  Changed paths:
    M dist/ExtUtils-ParseXS/lib/perlxstut.pod

  Log Message:
  -----------
  GH #18163: Stricter, cleaned up test example:

This just adds 'my $i' to make the test pass on strict, and it cleans
it up and provides test names for the tests.

I kept the tabs that were used.