Clean up 'cl-' prefixes for local variables

Clean up 'cl-' prefixes for local variables

The 'cl-' prefixes used for let-bound variables and argument names is a
holdover from the dynbind days.  They are no longer necessary, and make
the code hard to read.  This was partially cleaned up in the past; let's
finish the job now.

* lisp/emacs-lisp/cl-extra.el (cl--mapcar-many, cl-map, cl-maplist)
(cl-mapc, cl-mapl, cl-mapcan, cl-mapcon, cl-some, cl-every, cl-notany)
(cl-notevery, cl--map-keymap-recursively, cl--map-intervals)
(cl--map-overlays):
* lisp/emacs-lisp/cl-lib.el (cl-mapcar, cl-adjoin, cl-subst)
(cl--do-subst):
* lisp/emacs-lisp/cl-macs.el (cl--parse-loop-clause):
* lisp/emacs-lisp/cl-seq.el (cl-reduce, cl-fill, cl-replace, cl-remove)
(cl-remove-if, cl-remove-if-not, cl-delete, cl-delete-if)
(cl-delete-if-not, cl-remove-duplicates, cl-delete-duplicates)
(cl--delete-duplicates, cl-substitute, cl-substitute-if)
(cl-substitute-if-not, cl-nsubstitute, cl-nsubstitute-if)
(cl-nsubstitute-if-not, cl-find, cl-find-if, cl-find-if-not)
(cl-position, cl--position, cl-position-if, cl-position-if-not)
(cl-count, cl-count-if, cl-count-if-not, cl-mismatch, cl-search)
(cl-sort, cl-stable-sort, cl-merge, cl-member, cl-member-if)
(cl-member-if-not, cl--adjoin, cl-assoc, cl-assoc-if, cl-assoc-if-not)
(cl-rassoc, cl-rassoc-if, cl-rassoc-if-not, cl-union, cl-nunion)
(cl-intersection, cl-nintersection, cl-set-difference)
(cl-nset-difference, cl-set-exclusive-or, cl-nset-exclusive-or)
(cl-subsetp, cl-subst-if, cl-subst-if-not, cl-nsubst, cl-nsubst-if)
(cl-nsubst-if-not, cl-sublis, cl--sublis-rec, cl-nsublis)
(cl--nsublis-rec, cl-tree-equal, cl--tree-equal-rec): Clean up 'cl-'
prefixes for let-bound variables and arguments.

(cherry picked from commit 8c8ff13e7bdaab1446873d3401fe1a53a827198d)