Support for the new hashing algorithms in ZFS was introduced in r289422
However it was disconnected because FreeBSD lacked implementations of
SHA-512 (truncated to 256 bits), and Skein.
These implementations were introduced in r300921 and r300966 respectively
This commit connects them to ZFS and enabled these new checksum algorithms
This new algorithms are not supported by the boot blocks, so do not use them
on your root dataset if you boot from ZFS.
Relnotes: yes
Sponsored by: ScaleEngine Inc.
