Convert to USES=libtool and INSTALL_TARGET=install-strip
- Update to 20.1
Test::CleanNamespaces lets you check your module's namespaces for imported
functions you might have forgotten to remove with namespace::autoclean or
namespace::clean and are therefore available to be called as methods, which
usually isn't want you want.

WWW: http://search.cpan.org/dist/Test-CleanNamespaces/
- Add USES=libtool and INSTALL_TARGET=install-strip
- Replace LDFLAGS with LIBS
- Avoid including bsd.port.options.mk