devel/leiningen: Update to 2.11.1, update MAINTAINER

Update devel/leiningen to latest 2.11.1 and update MAINTAINER, taking ownership.

This update introduces a patch, as the main script for leiningen (bin/lein-pkg,
installed as $PREFIX/bin/lein) has changed significantly, adding more
bash-specific constructs. Handling them in a succession of sed commands was
getting more delicate than necessary; a patch seemed the better option here.

New maintainer already maintaining some ports.

PR: 276751
Reported by: beastieboy@beastieboy.net