This fixes vc-hg-print-log's choice of -r arguments to 'hg log'.
* lisp/vc/vc.el (vc-log-view-type): New 'log-outstanding' value.
(vc-log-outstanding): Pass it.
* lisp/vc/vc-git.el (vc-git-log-view-mode):
* lisp/vc/vc-hg.el (vc-hg-print-log, vc-hg-log-view-mode): Treat
'log-outstanding' the same as 'log-outgoing'.