A couple issues with Module::Build support:
1. Most modules include both a Build.PL and a
Makefile.PL (for backwards compatibility). cpan2rpm
currently checks for Makefile.PL first, and then
assumes MakeMaker semantics. The check order should be
2. The one Module::Build module you can't currently
package is....Module::Build itself. Unless you have it
installed already, cpan2rpm dies during the metadata phase.
This patch fixes both issues.