(ibuffer-compile-make-eliding-form, ibuffer-check-formats): Use
`with-no-warnings' to hide references to `ibuffer-elide-long-columns' (which is
defined on ibuffer.el, so it's silly to get warnings for it).
(ibuffer-auto-mode, ibuffer-cached-filter-formats,
ibuffer-compiled-filter-formats, ibuffer-filter-format-alist,
ibuffer-filter-group-kill-ring, ibuffer-filter-groups,
ibuffer-filtering-qualifiers, ibuffer-hidden-filter-groups,
ibuffer-inline-columns, ibuffer-show-empty-filter-groups,
ibuffer-tmp-hide-regexps, ibuffer-tmp-show-regexps): Defvar at compile time.
(ibuffer-compiled-formats, ibuffer-cached-eliding-string,
ibuffer-cached-formats, ibuffer-cached-elide-long-columns), eclare them before
use.