Merge branch 'ps/object-counting' into ps/odb-generic-object-name-handling

* ps/object-counting: object-file: fix sparse 'plain integer as NULL pointer' error 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"