(top-level): Don't require comint when compiling.

(top-level): Don't require comint when compiling.
(nslookup-font-lock-keywords): Don't require font-lock.
Use font-lock faces rather than variables.
(nslookup, ftp, smbclient, network-service-connection):
Don't require comint.
(comint-prompt-regexp, comint-input-autoexpand)
(comint-input-ring): Declare for compiler.
(comint-mode, ffap-string-at-point, comint-exec): Autoload.
(dns-lookup-host): Don't require ffap.  Remove `with-no-warnings'.