ExtUtils::MakeMaker::bytes - Version-agnostic bytes.pm
use just like bytes.pmbytes.pm was introduced with 5.6. This means any code which has 'use bytes' in it won't even compile on 5.5.X. Since bytes is a lexical pragma and must be used at compile time we can't simply wrap it in a BEGIN { eval 'use bytes' } block.
ExtUtils::MakeMaker::bytes is just a very thin wrapper around bytes which works just like it when bytes.pm exists and everywhere else it does nothing.