wt-status: convert struct wt_status to object_id

Change struct wt_status to use struct object_id instead of an array of
unsigned char.

Signed-off-by: brian m. carlson <sandals@crustytoothpaste.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

wt-status.c

@@ -2025,7 +2025,7 @@ static void wt_porcelain_v2_print_tracking(struct wt_status *s)
 	char eol = s->null_termination ? '\0' : '\n';
 
 	fprintf(s->fp, "# branch.oid %s%c",
-			(s->is_initial ? "(initial)" : sha1_to_hex(s->sha1_commit)),
+			(s->is_initial ? "(initial)" : oid_to_hex(&s->oid_commit)),
 			eol);
 
 	if (!s->branch)