Silence the rest of vc compilation

Silence the rest of vc compilation

* vc/vc-cvs.el (vc-exec-after, vc-coding-system-for-diff, vc-resynch-buffer):
Declare.
(vc-switches, vc-default-revert, vc-version-backup-file): Autoload.

* vc/vc-git.el (vc-exec-after, vc-set-async-update, grep-read-regexp)
(grep-read-files, grep-expand-template, vc-dir-refresh): Declare.
(vc-setup-buffer, vc-switches, vc-resynch-buffer): Autoload.

* vc/vc-hg.el (vc-exec-after, vc-set-async-update): Declare.
(vc-setup-buffer, vc-switches, vc-do-async-command): Autoload.

* vc/vc-sccs.el (vc-file-tree-walk): Declare.
(vc-expand-dirs, vc-switches, vc-setup-buffer, vc-delistify)
(vc-tag-precondition, vc-rename-master): Autoload.