* lisp/vc/vc-dispatcher.el (vc-compilation-mode): Add, based on

* lisp/vc/vc-dispatcher.el (vc-compilation-mode): Add, based on
vc-bzr-pull & vc-bzr-merge-branch.
* lisp/vc/vc-bzr.el (vc-bzr-pull, vc-bzr-merge-branch): Use it.
(vc-bzr-error-regexp-alist): Rename from vc-bzr-error-regex-alist
for consistency with compilation-error-regexp-alist.
* lisp/vc/vc-git.el (vc-git-error-regexp-alist): Add.
(vc-git-pull, vc-git-merge-branch): Call vc-compilation-mode.
* lisp/vc/vc-hg.el (vc-hg-error-regexp-alist): Add.
(vc-hg-pull, vc-hg-merge-branch): Call vc-compilation-mode.