Pugs/src/perl6/Prelude.pm unused

[coke]

Deleting this file has no impact on the build or the spectests. Can we delete it?

Some documentation in HACKING explaining how the Prelude is constructed and used at runtime would be helpful.

[audreyt]

The proper solution is to include the pm2c packer script that was lost during the svn=>Pugs.hs merge, and generate ./cbits/Prelude_pm.c whenever ./src/perl6/Prelude.pm changes.