* lisp/erc/erc.el: Commit c2d657e7c4
"Move ERC's core dependencies to a separate file" ironed out ERC's
interwoven dependencies for the better but didn't cleanly sidestep the
goodies interdependency, specifically with regard to custom options.
This reverts the tiny portion impacting this aspect by once again
requiring `erc-goodies' at the very end of ERC's main library. Special
thanks to Libera.Chat user jrm for reporting this bug.