Log message:
archivers: Replace RMD160 checksums with BLAKE2s checksums

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

Could not be committed due to merge conflict:
devel/py-traitlets/distinfo

The following distfiles were unfetchable (note: some may be only fetched
conditionally):

./devel/pvs/distinfo pvs-3.2-solaris.tgz
./devel/eclipse/distinfo eclipse-sourceBuild-srcIncluded-3.0.1.zip

Log message:
devel: Remove SHA1 hashes for distfiles

Log message:
tl-expected: Fix build without git

Log message:
devel: Add tl-expected

Single header implementation of std::expected with functional-style extensions.

std::expected is proposed as the preferred way to represent object which
will either have an expected value, or an unexpected value giving information
about why something failed. Unfortunately, chaining together many computations
which may fail can be verbose, as error-checking code will be mixed in with
the actual programming logic. This implementation provides a number of
utilities to make coding with expected cleaner.