Let ns load common-win.

Let ns load common-win.

* lisp/term/common-win.el (x-select-enable-clipboard):
* lisp/term/pc-win.el (x-select-enable-clipboard): Doc fix.

* lisp/term/ns-win.el: No need to require cl when compiling.
(x-display-name, x-setup-function-keys, x-select-text, x-colors)
(xw-defined-colors): Use the common-win definitions.
(ns-alternatives-map): Make it an obsolete alias for x-alternatives-map.
(ns-handle-iconic): Make it an alias for x-handle-iconic.
* lisp/term/common-win.el (x-select-text, x-alternatives-map)
(x-setup-function-keys, x-colors, xw-defined-colors): Handle 'ns case.
* lisp/loadup.el [ns]: Load common-win.