Merge branch 'sb/object-store'

Refactoring the internal global data structure to make it possible
to open multiple repositories, work with and then close them.

Rerolled by Duy on top of a separate preliminary clean-up topic.
The resulting structure of the topics looked very sensible.

* sb/object-store: (27 commits)
  sha1_file: allow sha1_loose_object_info to handle arbitrary repositories
  sha1_file: allow map_sha1_file to handle arbitrary repositories
  sha1_file: allow map_sha1_file_1 to handle arbitrary repositories
  sha1_file: allow open_sha1_file to handle arbitrary repositories
  sha1_file: allow stat_sha1_file to handle arbitrary repositories
  sha1_file: allow sha1_file_name to handle arbitrary repositories
  sha1_file: add repository argument to sha1_loose_object_info
  sha1_file: add repository argument to map_sha1_file
  sha1_file: add repository argument to map_sha1_file_1
  sha1_file: add repository argument to open_sha1_file
  sha1_file: add repository argument to stat_sha1_file
  sha1_file: add repository argument to sha1_file_name
  sha1_file: allow prepare_alt_odb to handle arbitrary repositories
  sha1_file: allow link_alt_odb_entries to handle arbitrary repositories
  sha1_file: add repository argument to prepare_alt_odb
  sha1_file: add repository argument to link_alt_odb_entries
  sha1_file: add repository argument to read_info_alternates
  sha1_file: add repository argument to link_alt_odb_entry
  sha1_file: add raw_object_store argument to alt_odb_usable
  pack: move approximate object count to object store
  ...

builtin/receive-pack.c

@@ -2027,7 +2027,7 @@ int cmd_receive_pack(int argc, const char **argv, const char *prefix)
 			proc.git_cmd = 1;
 			proc.argv = argv_gc_auto;
 
-			close_all_packs();
+			close_all_packs(the_repository->objects);
 			if (!start_command(&proc)) {
 				if (use_sideband)
 					copy_to_sideband(proc.err, -1, NULL);