object.c: free replace map in raw_object_store_clear

The replace map for objects was missed to free in the object store in
the conversion of 174774cd51 (Merge branch 'sb/object-store-replace',
2018-05-08)

Signed-off-by: Stefan Beller <sbeller@google.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

object.c

@@ -480,6 +480,7 @@ void raw_object_store_clear(struct raw_object_store *o)
 {
 	FREE_AND_NULL(o->objectdir);
 	FREE_AND_NULL(o->alternate_db);
+	FREE_AND_NULL(o->replace_map);
 
 	free_alt_odbs(o);
 	o->alt_odb_tail = NULL;