Merge branch 'tb/unsafe-hash-cleanup'

The API around choosing to use unsafe variant of SHA-1 implementation has been updated in an attempt to make it harder to abuse. * tb/unsafe-hash-cleanup: hash.h: drop unsafe_ function variants csum-file: introduce hashfile_checkpoint_init() t/helper/test-hash.c: use unsafe_hash_algo() csum-file.c: use unsafe_hash_algo() hash.h: introduce `unsafe_hash_algo()` csum-file.c: extract algop from hashfile_checksum_valid() csum-file: store the hash algorithm as a struct field t/helper/test-tool: implement sha1-unsafe helper