Work on private copy of environment in precompile.
Work on private copy of environment in precompile.

Avoids data races and over-sharing of the %*ENV hash, and allows us
to eliminate cleanup logic.

softmoth/rakudo,nbrown/rakudo,awwaiid/rakudo,jonathanstowe/rakudo,labster/rakudo,lucasbuchala/rakudo,MasterDuke17/rakudo,rakudo/rakudo,lucasbuchala/rakudo,rakudo/rakudo,tbrowder/rakudo,tbrowder/rakudo,salortiz/rakudo,jonathanstowe/rakudo,jonathanstowe/rakudo,labster/rakudo,tbrowder/rakudo,tony-o/rakudo,MasterDuke17/rakudo,raydiak/rakudo,jonathanstowe/rakudo,tony-o/rakudo,sjn/rakudo,labster/rakudo,tbrowder/rakudo,Gnouc/rakudo,Gnouc/rakudo,sjn/rakudo,Gnouc/rakudo,Gnouc/rakudo,softmoth/rakudo,rakudo/rakudo,usev6/rakudo,rakudo/rakudo,rakudo/rakudo,tony-o/rakudo,usev6/rakudo,salortiz/rakudo,labster/rakudo,raydiak/rakudo,MasterDuke17/rakudo,usev6/rakudo,MasterDuke17/rakudo,tony-o/rakudo,awwaiid/rakudo,raydiak/rakudo,nbrown/rakudo,softmoth/rakudo,usev6/rakudo,usev6/rakudo,awwaiid/rakudo,MasterDuke17/rakudo,salortiz/rakudo,sjn/rakudo,labster/rakudo,salortiz/rakudo,lucasbuchala/rakudo,raydiak/rakudo,Gnouc/rakudo,MasterDuke17/rakudo,nbrown/rakudo,salortiz/rakudo,tony-o/rakudo,softmoth/rakudo,sjn/rakudo,labster/rakudo,lucasbuchala/rakudo,Gnouc/rakudo,awwaiid/rakudo,tbrowder/rakudo,sjn/rakudo,tony-o/rakudo,nbrown/rakudo,lucasbuchala/rakudo,rakudo/rakudo,jonathanstowe/rakudo,nbrown/rakudo,tbrowder/rakudo,softmoth/rakudo,nbrown/rakudo,awwaiid/rakudo,salortiz/rakudo