I decided to celebrate Perl birthday with several new tools. First one is 'eumm-upgrade'.
It can be used to allow using new features of ExtUtils::MakeMaker without losing compatibility with older versions. BUILD_REQUIRES is the main new feature (I wrote it). It is important for ActivePerl ppm files, for META.yml and for OS packages.
eumm-upgrade adds compatibility code to Makefile.PL and tries to automatically detect some properties like license, minimum Perl version required and repository used.
You can install App::EUMM::Upgrade from CPAN. Or just download version 0.21 from Github directly and install from CPAN these modules: File::Slurp Text::FindIndent Github::Fork::Parent ExtUtils::MakeMaker.
To use, run eumm-upgrade.pl in directory with Makefile.PL. Old file will be copied to Makefile.PL.bak. If you use Github repository, Internet connection is required.
You need to check resulting Makefile.PL manually as transformation is done with regular expressions.