Merge branch 'ps/object-counting'

The logic to count objects has been cleaned up.

* ps/object-counting:
  odb: introduce generic object counting
  odb/source: introduce generic object counting
  object-file: generalize counting objects
  object-file: extract logic to approximate object count
  packfile: extract logic to count number of objects
  odb: stop including "odb/source.h"

diff --cc builtin/gc.c
Simple merge

diff --cc builtin/multi-pack-index.c
Simple merge

diff --cc builtin/submodule--helper.c
Simple merge

diff --cc object-file.c
Simple merge

diff --cc repository.c
index 0b8f7ec20089e0c720affdf2913429bb8c0e14b4,05c26bdbc3bc08704bdc05705cb93c9a50ddbcc8..9e5537f53961ed3ace4135be10435b7054c12916
--- 1/repository.c
--- 2/repository.c
+++ b/repository.c
@@@ -1,10 -1,9 +1,11 @@@
  #include "git-compat-util.h"
  #include "abspath.h"
  #include "repository.h"
 +#include "hook.h"
  #include "odb.h"
+ #include "odb/source.h"
  #include "config.h"
 +#include "gettext.h"
  #include "object.h"
  #include "lockfile.h"
  #include "path.h"