* vc-arch.el (vc-arch-extra-menu-map): New var and fun.

* vc-arch.el (vc-arch-extra-menu-map): New var and fun.

* vc-hooks.el (vc-menu-entry): New var.
(vc-mode-line-map): Use it so that this menu also uses the extra-menu.
(menu-bar-tools-menu): Add the VC menu here rather than in menu-bar.el.
(vc-menu-map): Declare and initialize in one step.

* menu-bar.el (vc-menu-map): Don't setup any more.
Instead, just create the proper spot in the menu.

* vc.el: Document new VC operation `extra-menu'.

* vc-hooks.el (vc-default-extra-menu, vc-menu-map-filter): New
function.