(vc-exec-after): Move setting mode-line-process in the

(vc-exec-after): Move setting mode-line-process in the
busy case ...
(vc-set-mode-line-busy-indicator): ... in this new function.
(vc-status-refresh): Call vc-set-mode-line-busy-indicator.
(vc-update-vc-status-buffer): Reset mode-line-process.
(vc-status-mark-all-files, vc-status-unmark-all-files): Change to
mark/unmark all the files with the same state as the current one.
With a prefix argument mark/unmark all files.
(vc-status-mode-menu): Adjust strings.