* rs/unpack-trees-plug-leak:
unpack-trees: free cache_entry array members for merges
diff-lib, read-tree, unpack-trees: mark cache_entry array paramters const
diff-lib, read-tree, unpack-trees: mark cache_entry pointers const
unpack-trees: create working copy of merge entry in merged_entry
unpack-trees: factor out dup_entry
read-cache: mark cache_entry pointers const
cache: mark cache_entry pointers const