Fix loading modules from the Staging repo during precompilation
Fix loading modules from the Staging repo during precompilation

When we change the repo chain after the fact (as in load a precompiled
CompUnit::Repository::Staging and then try to load precomp files from
there) a new CompUnit::PrecompilationRepository gets created and used.
This new precompilation repository would not know about modules loaded
by the one used earlier causing precompilation processes to fail.

Fix by sharing the %loaded hash between precompilation repository
instances.

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