Merge branch 'bc/sha-256'
Add sha-256 hash and plug it through the code to allow building Git
with the "NewHash".
* bc/sha-256:
hash: add an SHA-256 implementation using OpenSSL
sha256: add an SHA-256 implementation using libgcrypt
Add a base implementation of SHA-256 support
commit-graph: convert to using the_hash_algo
t/helper: add a test helper to compute hash speed
sha1-file: add a constant for hash block size
t: make the sha1 test-tool helper generic
t: add basic tests for our SHA-1 implementation
cache: make hashcmp and hasheq work with larger hashes
hex: introduce functions to print arbitrary hashes
sha1-file: provide functions to look up hash algorithms
sha1-file: rename algorithm to "sha1"