Update from version 0.5000 to version 0.5100 (upstream version 0.51)

Pkgsrc changes:
- Switch PERL5_MODULE_TYPE to Module::Build

Upstream changes:
0.51  2009-11-01
- Switched to Module::Build. To force a non-XS build, start the build
  process with "perl Build.PL --pp".
- POD-related tests are only run for the maintainer now.
- Fixed handling of negative years in CLDR formatting for "y" and "u"
  patterns. Note that the LDML spec says nothing about how this should work,
  so I took my best guess.

(seb)