Prefer setq-local in lisp/mh-e/*.el

Prefer setq-local in lisp/mh-e/*.el

* lisp/mh-e/mh-utils.el (mh-make-local-vars): Make obsolete.
* lisp/mh-e/mh-comp.el (mh-forward):
* lisp/mh-e/mh-folder.el (mh-folder-mode):
* lisp/mh-e/mh-identity.el (mh-identity-handler-signature)
(mh-identity-insert-attribution-verb):
* lisp/mh-e/mh-letter.el (mh-letter-mode):
* lisp/mh-e/mh-search.el (mh-search-folder):
* lisp/mh-e/mh-seq.el (mh-narrow-to-seq, mh-widen):
* lisp/mh-e/mh-show.el (mh-show-mode):
* lisp/mh-e/mh-tool-bar.el (mh-tool-bar-define):
* lisp/mh-e/mh-xface.el (mh-x-image-url-display)
(mh-x-image-url-fetch-image): Prefer setq-local.