Convert struct ref_array_item to struct object_id

Convert struct ref_array_item to struct object_id

Convert struct ref_array_item to use struct object_id by changing the
definition and applying the following semantic patch, plus the standard
object_id transforms:

@@
struct ref_array_item E1;
@@
- E1.objectname
+ E1.objectname.hash

@@
struct ref_array_item *E1;
@@
- E1->objectname
+ E1->objectname.hash

This transformation allows us to convert get_obj, which is needed to
convert parse_object_buffer.

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