emerge --info: Always print ::repository.

1 call to deprecated portage.repository.config.RepoConfigLoader.mainRepo() function
has been deleted.
emerge --verbose --quiet-repo-display: Delete deprecated code.

Use portage.repository.config.RepoConfigLoader.__iter__() instead of deprecated
PORTDIR and PORTDIR_OVERLAY.
1 call to deprecated portage.repository.config.RepoConfigLoader.mainRepoLocation()
function has been deleted.