Merge branch 'tr/packed-object-info-wo-recursion'

Attempts to reduce the stack footprint of sha1_object_info()
and unpack_entry() codepaths.

* tr/packed-object-info-wo-recursion:
  sha1_file: remove recursion in unpack_entry
  Refactor parts of in_delta_base_cache/cache_or_unpack_entry
  sha1_file: remove recursion in packed_object_info

Author: gitster