(top-level): Clean up

(top-level): Clean up
`eval-when-compile's and assorted defvars.
(cperl-invalid-face): Don't double-quote value.  Change custom
type.
(cperl-mode): Set normal-auto-fill-function and don't zap
auto-fill-function.
(cperl-imenu--function-name-regexp-perl): Renamed from
imenu-example--function-name-regexp-perl.
(cperl-imenu--create-perl-index): Renamed from
imenu-example--create-perl-index.
(cperl-xsub-scan): Don't require cl.