liblzma: SHA-256: Unroll a little more.
liblzma: SHA-256: Unroll a little more.

This way a branch isn't needed for each operation
to choose between blk0 and blk2, and still the code
doesn't grow as much as it would with full unrolling.

pombreda/go-liblzma,pombreda/go-liblzma,pombreda/go-liblzma