merge-recursive: Allow make_room_for_path() to remove D/F entries
If there were several files conflicting below a directory corresponding
to a D/F conflict, and the file of that D/F conflict is in the way, we
want it to be removed. Since files of D/F conflicts are handled last,
they can be reinstated later and possibly with a new unique name.
Signed-off-by: Elijah Newren <newren@gmail.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>