Merge branch 'jk/pack-name-cleanups' into maint

Code clean-up.

* jk/pack-name-cleanups:
  index-pack: make pointer-alias fallbacks safer
  replace snprintf with odb_pack_name()
  odb_pack_keep(): stop generating keepfile name
  sha1_file.c: make pack-name helper globally accessible
  move odb_* declarations out of git-compat-util.h

diff --cc cache.h
Simple merge

diff --cc environment.c
Simple merge

diff --cc git-compat-util.h
Simple merge

diff --cc sha1_file.c
Simple merge