merge_recursive: Fix renames across paths below D/F conflicts

merge_recursive: Fix renames across paths below D/F conflicts

The rename logic in process_renames() handles renames and merging of file
contents and then marks files as processed.  However, there may be higher
stage entries left in the index for other reasons (e.g., due to D/F
conflicts).  By checking for such cases and marking the entry as not
processed, it allows process_entry() later to look at it and handle those
higher stages.

Signed-off-by: Elijah Newren <newren@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>