* lisp/org/: Delete some always-nil variables

* lisp/org/: Delete some always-nil variables

* lisp/org/ob-lilypond.el (org-babel-lilypond-compile-lilyfile):
Remove always-nil variable `arg-2`.

* lisp/org/ol-gnus.el (org-gnus-store-link):
Remove always-nil variables `newsgroup` and `xarchive`.

* lisp/org/ol.el (org-store-link):
Remove always-nil variable `description`.

* lisp/org/org-clock.el (org-clock-special-range):
Remove always-nil variables `m1` and `m`.

* lisp/org/org-crypt.el (org--matcher-tags-todo-only): Declare var.

* lisp/org/org-protocol.el (org-protocol-open-source):
Remove always-nil variable `result`.

* lisp/org/ox-odt.el (org-odt-format-label):
Remove always-nil variable `short-caption`.
(org-odt-link--inline-formula):
Remove always-nil variables `width` and `height`.

* lisp/org/ox.el (org-export--missing-definitions):
Remove always-nil variable `seen`.