Remove some bogus definition-prefixes from loaddefs

* lisp/emacs-lisp/autoload.el (autoload-generate-file-autoloads):
Don't register a definition prefix from define-erc-module,
which adds an erc- prefix to its argument.

lisp/emacs-lisp/autoload.el

@@ -761,6 +761,7 @@ FILE's modification time."
                                      "def-edebug-spec"
                                      ;; Hmm... this is getting ugly:
                                      "define-widget"
+                                     "define-erc-module"
                                      "define-erc-response-handler"
                                      "defun-rcirc-command"))))
                     (push (match-string 2) defs))