feat: build diffutils binaries

[kormide]

Build all diffutils binaries for linux (glibc) and macos. The intention moving forward is to build the linux binaries using musl and to add windows/arm64.

Release workflow to come in a follow-up.

[kormide]

@dzbarsky will revisit musl after that include ordering issue is fixed in toolchains_llvm_bootstrapped. I'll open an issue for that.

[dzbarsky]

see comments about glic versioning, that is pretty important if you want the tools usable on older glibcs

[kormide]

Got macos amd64 working. Put it here as well as in the BCR entry.

[kormide]

Filed hermeticbuild/hermetic-llvm#339 for the musl includes issue.

[alexeagle]

neat, I guess we'll add GitHub Actions automation to publish artifacts to releases?

[kormide]

neat, I guess we'll add GitHub Actions automation to publish artifacts to releases?

Yep, I'll do that in a follow-up. I'm working on Windows tonight so I'll try to add that before landing this.

[kormide]

Got Windows amd64 working. Unfortunately it can't go into the BCR because the downstream @sed dependency doesn't work on Windows. For now I've just patched it in here.

[kormide]

Added CI. I'll merge this in and add releases in a follow-up.