vendor github.com/bazelbuild/buildtools/{build,tables} (#145)

github.com/bazelbuild/buildtools/build is undergoing significant
changes which break backward compatibility. This will stop Gazelle
from being built with "go get".

buildtools is vendored at 80c7f0d45d7e40fa1f7362852697d4a03df557b3,
which was the version we were using before.
22 files changed