Merge branch 'mf/revision-max-count-oldest' into seen

"git rev-list" (and "git log" family of commands) learned a new "--max-count-oldest"
that picks oldest N commits in the range instead of the usual newest.

* mf/revision-max-count-oldest:
  revision.c: implement --max-count-oldest

diff --cc Documentation/rev-list-options.adoc
Simple merge

diff --cc revision.c
Simple merge

diff --cc revision.h
Simple merge