More transition from "unsigned char[40]" to "struct object_id".
This needed a few merge fixups, but is mostly disentangled from other
topics.
* bc/object-id:
remote: convert functions to struct object_id
Remove get_object_hash.
Convert struct object to object_id
Add several uses of get_object_hash.
object: introduce get_object_hash macro.
ref_newer: convert to use struct object_id
push_refs_with_export: convert to struct object_id
get_remote_heads: convert to struct object_id
parse_fetch: convert to use struct object_id
add_sought_entry_mem: convert to struct object_id
Convert struct ref to use object_id.
sha1_file: introduce has_object_file helper.