Move GH_TUPLE to Makefile.gh_tuple to make regeneration easier.
Include WORKSPACE in the list of files to pull dependencies from
This bug discusses possibly using local_repository instead:
https://github.com/bazelbuild/bazel/issues/4996
Setup for io_bazel_rules_closuer describes entries in WORKSPACE,
which is how I got the idea to add it
https://github.com/bazelbuild/rules_closure