odb: drop gaps in object info flag values

The object info flag values have a two gaps in their definitions, where
some bits are skipped over. These gaps don't really hurt, but it makes
one wonder whether anything is going on and whether a subset of flags
might be defined somewhere else.

That's not the case though. Instead, this is a case of flags that have
been dropped in the past:

  - The value 4 was used by `OBJECT_INFO_SKIP_CACHED`, removed in
    9c8a294 (sha1-file: remove OBJECT_INFO_SKIP_CACHED, 2020-01-02).

  - The value 8 was used by `OBJECT_INFO_ALLOW_UNKNOWN_TYPE`, removed in
    ae24b03 (object-file: drop OBJECT_INFO_ALLOW_UNKNOWN_TYPE flag,
    2025-05-16).

Close those gaps to avoid any more confusion.

Signed-off-by: Patrick Steinhardt <ps@pks.im>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

Author: pks-t

odb.h

@@ -353,22 +353,22 @@ struct object_info {
 #define OBJECT_INFO_INIT { 0 }
 
 /* Invoke lookup_replace_object() on the given hash */
-#define OBJECT_INFO_LOOKUP_REPLACE 1
+#define OBJECT_INFO_LOOKUP_REPLACE (1 << 0)
 /* Do not retry packed storage after checking packed and loose storage */
-#define OBJECT_INFO_QUICK 8
+#define OBJECT_INFO_QUICK (1 << 1)
 /*
  * Do not attempt to fetch the object if missing (even if fetch_is_missing is
  * nonzero).
  */
-#define OBJECT_INFO_SKIP_FETCH_OBJECT 16
+#define OBJECT_INFO_SKIP_FETCH_OBJECT (1 << 2)
 /*
  * This is meant for bulk prefetching of missing blobs in a partial
  * clone. Implies OBJECT_INFO_SKIP_FETCH_OBJECT and OBJECT_INFO_QUICK
  */
 #define OBJECT_INFO_FOR_PREFETCH (OBJECT_INFO_SKIP_FETCH_OBJECT | OBJECT_INFO_QUICK)
 
 /* Die if object corruption (not just an object being missing) was detected. */
-#define OBJECT_INFO_DIE_IF_CORRUPT 32
+#define OBJECT_INFO_DIE_IF_CORRUPT (1 << 3)
 
 /*
  * Read object info from the object database and populate the `object_info`