Merge branch 'nd/the-index-final'

The assumption to work on the single "in-core index" instance has
been reduced from the library-ish part of the codebase.

* nd/the-index-final:
  cache.h: flip NO_THE_INDEX_COMPATIBILITY_MACROS switch
  read-cache.c: remove the_* from index_has_changes()
  merge-recursive.c: remove implicit dependency on the_repository
  merge-recursive.c: remove implicit dependency on the_index
  sha1-name.c: remove implicit dependency on the_index
  read-cache.c: replace update_index_if_able with repo_&
  read-cache.c: kill read_index()
  checkout: avoid the_index when possible
  repository.c: replace hold_locked_index() with repo_hold_locked_index()
  notes-utils.c: remove the_repository references
  grep: use grep_opt->repo instead of explict repo argument

sequencer.h

@@ -126,7 +126,8 @@ int update_head_with_reflog(const struct commit *old_head,
 			    const struct object_id *new_head,
 			    const char *action, const struct strbuf *msg,
 			    struct strbuf *err);
-void commit_post_rewrite(const struct commit *current_head,
+void commit_post_rewrite(struct repository *r,
+			 const struct commit *current_head,
 			 const struct object_id *new_head);
 
 int prepare_branch_to_be_rebased(struct replay_opts *opts, const char *commit);