Merge branch 'rs/packfile-bad-object-list-in-oidset'

Merge branch 'rs/packfile-bad-object-list-in-oidset'

Replace a handcrafted data structure used to keep track of bad
objects in the packfile API by an oidset.

* rs/packfile-bad-object-list-in-oidset:
  packfile: use oidset for bad objects
  packfile: convert has_packed_and_bad() to object_id
  packfile: convert mark_bad_packed_object() to object_id
  midx: inline nth_midxed_pack_entry()
  oidset: make oidset_size() an inline function