remove undefined functions in future.h

[kikofernandez]

there are three functions declared in future.h with no definition. they should be removed.

[EliasC]

This seems like a reasonable thing to do. Merging later today.

[albertnetymk]

I am OK with merging this, but it would be better if this kind of “refactoring” could be done along with some real changes so that the PR review process is worth the effort.

[kikofernandez]

not sure I agree... what other real change can I add to this PR? I think it's better to have something rather than nothing. I found these by mistake...

1. should they be in another bigger PR which is not specific to this?
2. Should I wait until I find more issues similar to this one or I have time to do more refactoring?

I don't like 1 and I am not sure when I will have time to do 2. I think it's better to push a small change that takes 5 min to check and merge.

[EliasC]

I also think it's better to have these kind of changes in smaller PRs, otherwise it might be lost in review, and I might be looking for these function stubs I left in there 300 commits ago that were covertly removed in some unrelated PR.

Any kind of refactoring that could affect someone else's work (i.e. not whitespace/formatting) could be getting a PR of their own I think.