cache: convert struct cache_entry to use struct object_id

Convert struct cache_entry to use struct object_id by applying the
following semantic patch and the object_id transforms from contrib, plus
the actual change to the struct:

@@
struct cache_entry E1;
@@
- E1.sha1
+ E1.oid.hash

@@
struct cache_entry *E1;
@@
- E1->sha1
+ E1->oid.hash

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

builtin/ls-files.c

@@ -187,7 +187,7 @@ static void show_ce_entry(const char *tag, const struct cache_entry *ce)
 		printf("%s%06o %s %d\t",
 		       tag,
 		       ce->ce_mode,
-		       find_unique_abbrev(ce->sha1,abbrev),
+		       find_unique_abbrev(ce->oid.hash,abbrev),
 		       ce_stage(ce));
 	}
 	write_eolinfo(ce, ce->name);