Merge branch 'jk/pack-name-cleanups'

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 fast-import.c
Simple merge

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

diff --cc sha1_file.c
Simple merge