podcheck.t: Is problem if cpan/non-cpan have same NAME

podcheck.t: Is problem if cpan/non-cpan have same NAME

If a module whose upstream is cpan has the same NAME as a module that
isn't, that is a problem that should be warned about, as we shouldn't be
shipping two identically named modules, even if one is not under Perl
core's control.  (If two cpan modules have the same name, it is a
problem as well, but not anything we can do anything about, so warn only
when cpan warnings are enabled.)