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>

diff.c

@@ -2700,7 +2700,7 @@ static int reuse_worktree_file(const char *name, const unsigned char *sha1, int
 	 * This is not the sha1 we are looking for, or
 	 * unreusable because it is not a regular file.
 	 */
-	if (hashcmp(sha1, ce->sha1) || !S_ISREG(ce->ce_mode))
+	if (hashcmp(sha1, ce->oid.hash) || !S_ISREG(ce->ce_mode))
 		return 0;
 
 	/*