The previous method for checking this was generic, which is nice, but
sort of verbose to use.  Worse, though, I don't think it was reliable.
That code, ->file_updated_ok and ->file_not_updated_ok, worked by
keeping a cache of file stats -- but it didn't precompute those stats,
it computed them on demand.  So given this program:

  $pause = PAUSE::TestPause->new;

  do_stuff();
  my $r1 = $pause->test_reindex;
  do_other_stuff();
  $pause->file_updated_ok("A");
  my $r2 = $pause->test_reindex;
  do_more_stuff();
  my $r3 = $pause->test_reindex;

Calling `->file_updated_ok("A")` at the end would test since the
previous call.  Calling `->file_updated_ok("B")` at the end would test
starting from nothing.

In reality, we only use this method for tracking 02packages, so I've
added specific tracking of that file, with the check put onto the Result
object, considering only what changed in the `test_reindex` call that
created that Result.

(I want to test files we can't extract.)

...and add methods to check or print them.

(Specificaly: it is perl-like, not unauthorized real perl.)

That is: a new relase of perl-5, even if it contains a higher version of
some dual-life package, should not replace the old package in the index,
if it comes from a non-perl distribution.

This will not work until Module-Faker with chmod 0644-ing of files is
released.