Silence some compiler warnings

Silence some compiler warnings

* calculator.el (electric, ehelp): No need to load when compiling.
(Electric-command-loop, electric-describe-mode): Declare.

* doc-view.el (doc-view-current-converter-processes): Move before use.

* files.el (dired-unmark):
* progmodes/gud.el (gdb-input): Update declarations.

* emacs-lisp/easy-mmode.el (define-globalized-minor-mode):
Move MODE-set-explicitly definition before use.

* erc/erc-log.el (erc-network-name): Declare.

* erc/erc-notify.el (pcomplete--here): Declare.
(pcomplete/erc-mode/NOTIFY): Require pcomplete.

* international/mule-diag.el (mule-diag):
Don't use obsolete window-system-version.

* mail/feedmail.el (smtpmail): No need to load when compiling.
(smtpmail-via-smtp, smtpmail-smtp-server): Declare.

* mail/mail-utils.el (rfc822): No need to load when compiling.
(rfc822-addresses): Autoload it.
(mail-strip-quoted-names): Trivial simplification.

* mail/rmail.el (rmail-mime-message-p, rmail-mime-toggle-raw): Declare.
(rmail-retry-failure): Don't assume that rmail-mime-feature == rmailmm.

* net/snmp-mode.el (tempo): Don't duplicate requires.

* progmodes/prolog.el (info): No need to load when compiling.
(comint): Require before shell requires it.
(Info-goto-node): Autoload it.
(Info-follow-nearest-node): Declare.
(prolog-help-info, prolog-goto-predicate-info): No need to require info.

* textmodes/artist.el (picture-mode-exit): Declare.

* textmodes/reftex-parse.el (reftex-parse-from-file):
Trivial rewrite so the compiler can parse it better.

* url/url-dav.el (url-http): Require it.
(url-http-head-file-attributes): Don't autoload it.

* url/url-proxy.el (url-http): Autoload it.