cmd/dist: cmd/internal/objabi/zbootstrap.go is not removed

[perillo]

I noted that on Linux amd64, with go1.14beta1-137-g71239b4f49, after calling make.bash, clean.bash does not remove the file cmd/internal/objabi/zbootstrap.go.

I have confirmed the problem using git status --ignored.

[toothrot]

I think that is supposed to be cleaned up by go tool dist clean, but I am not positive.

/cc @bcmills @jayconrod

[ianlancetaylor]

I bet that "cmd/internal/objabi" should be added to cleanlist in cmd/dist/build.go.

[SataQiu]

I'm willing to have a try!

[gopherbot]

Change https://golang.org/cl/216222 mentions this issue: cmd/dist: fix the bug that cmd/internal/objabi/zbootstrap.go could not be cleaned properly

[perillo]

@SataQiu I suggest to change the commit message to
cmd/dist: ensure that cmd/internal/objabi/zbootstrap.go is cleaned properly

Thanks