Log message:
sysutils: Replace RMD160 checksums with BLAKE2s checksums

All checksums have been double-checked against existing RMD160 and
SHA512 hashes

Log message:
sysutils: Remove SHA1 hashes for distfiles

Log message:
sysutils/rw: import rw-1.0

Sortix rw is a program that reads blocks from the standard input and copies them
to the standard output until the end of the standard input. rw(1) is designed to
be a replacement for dd(1), providing only the the core blockwise I/O. It has a
standard command line interface with dashed options, useful and efficient
defaults, and is simpler because it doesn't support converting the input (e.g.
converting ASCII to/from EBCDIC).