Moo::Role-related bug in Perl 5.8.1 through 5.8.3

[patch]

Most releases of CLDR::Number have had inconsistent but common Moo::Role-related test failures in Perl v5.8.1 through v5.8.3. The oldest version of Perl that has not been known to have this problem is v5.8.4, although there are very few reports on that version.

We should either figure out the problem and fix it, or raise the minimum version of Perl from v5.8.1 (September 2003) to v5.8.4 (April 2004), which I would not be against.

Test reports:
http://matrix.cpantesters.org/?dist=CLDR-Number+0.19

Typical output:

Use of uninitialized value in method lookup at /home/njh/perl5/perlbrew/perls/perl-5.8.1/lib/site_perl/5.8.1/Moo/Role.pm line 138.
Use of uninitialized value in method lookup at /home/njh/perl5/perlbrew/perls/perl-5.8.1/lib/site_perl/5.8.1/Moo/Role.pm line 138.
Can't locate object method "is_role" via package "Moo::Role" at /home/njh/perl5/perlbrew/perls/perl-5.8.1/lib/site_perl/5.8.1/Moo/Role.pm line 138.
BEGIN failed--compilation aborted at /home/njh/.cpan/build/CLDR-Number-0.19-M6Ajmp/blib/lib/CLDR/Number/Role/Format.pm line 13.
Compilation failed in require at /home/njh/perl5/perlbrew/perls/perl-5.8.1/lib/site_perl/5.8.1/Module/Runtime.pm line 313.
Compilation failed in require at /home/njh/.cpan/build/CLDR-Number-0.19-M6Ajmp/blib/lib/CLDR/Number.pm line 32.