New buffer-local vc-buffer-overriding-fileset and vc-buffer-revision

New buffer-local vc-buffer-overriding-fileset and vc-buffer-revision

* lisp/vc/vc.el (vc-buffer-overriding-fileset)
(vc-buffer-revision): New variables (bug#77529).
(vc-find-revision-save, vc-find-revision-no-save): Set them.
(vc-deduce-fileset): Respect vc-buffer-overriding-fileset.
(vc-print-log): Use vc-buffer-revision as a default working
revision.

* lisp/vc/vc-annotate.el (vc-annotate-parent-file)
(vc-annotate-parent-rev): Delete.
(vc-annotate): Respect vc-buffer-overriding-fileset and
vc-buffer-revision.  This makes 'C-x v g' work from buffers
generated by 'C-x v ~' (bug#5424).
Set the two variables in the newly prepared buffer.
(vc-annotate-working-revision)
(vc-annotate-extract-revision-at-line)
(vc-annotate-revision-at-line, vc-annotate-warp-revision)
(vc-annotate-goto-line):
* lisp/vc/vc-svn.el (vc-svn-annotate-current-time): Use
vc-buffer-overriding-fileset instead of vc-annotate-parent-file,
vc-buffer-revision instead of vc-annotate-parent-rev.
(vc-annotate-parent-rev): Delete declaration.

* etc/NEWS: Announce the new variables.

(cherry picked from commit 60530889c309746def95f32d3dfc117bc4f98444)