New functions plusp and minusp

New functions plusp and minusp

* lisp/emacs-lisp/cl-lib.el (cl-plusp, cl-minusp): Move from here...
* lisp/subr.el (plusp, minusp): ...to here.  Make old names into
aliases, documented as deprecated.  Add type declarations.  Change from
defsubst to regular functions with compiler macros.
* lisp/obsolete/cl.el: Don't alias plusp and minusp.

* test/lisp/emacs-lisp/cl-lib-tests.el (cl-lib-test-plusp)
(cl-lib-test-minusp): Move tests from here...
* test/lisp/subr-tests.el (subr-test-plusp, subr-test-minusp):
...to here.

* doc/lispref/numbers.texi (Predicates on Numbers): Document plusp
and minusp.
* doc/misc/cl.texi (Predicates on Numbers): Delete cl-plusp and
cl-minusp.
* lisp/emacs-lisp/shortdoc.el (number): Document plusp and minusp
instead of cl-plusp and cl-minusp.

(cherry picked from commit afbf932106fdd1043b0debe9fc9134e031e4c9a6)