We add a new make goal called release-install that creates the same
reproducible binaries as the release script would create, but only for
the current OS/architecture. It then installs those binaries to the
system's GOBIN directory.
To allow easy verification of individual binaries (instead of just the
packag tarballs/zips), we also add the hashes of lnd and lncli binaries
to the manifest. We do the same in the docker build.