* jk/oid-array-cleanup:
commit-graph: use size_t for array allocation and indexing
commit-graph: replace packed_oid_list with oid_array
commit-graph: drop count_distinct_commits() function
oid-array: provide a for-loop iterator
oid-array: make sort function public
cache.h: move hash/oid functions to hash.h
t0064: make duplicate tests more robust
t0064: drop sha1 mention from filename
oid-array.h: drop sha1 mention from header guard