Add --relative-date option to the revision interface

Exposes the infrastructure from 9a8e35e98793af086f05d1ca9643052df9b44a74.

Signed-off-by: Jonas Fonseca <fonseca@diku.dk>
Signed-off-by: Junio C Hamano <junkio@cox.net>
diff --git a/revision.h b/revision.h
index 0c3b8d9..d289781 100644
--- a/revision.h
+++ b/revision.h
@@ -55,7 +55,8 @@
 
 	/* Format info */
 	unsigned int	shown_one:1,
-			abbrev_commit:1;
+			abbrev_commit:1,
+			relative_date:1;
 	unsigned int	abbrev;
 	enum cmit_fmt	commit_format;
 	struct log_info *loginfo;