Change in coreboot[master]: lib/future: Implement Futures API

[Martin Roth (Code Review)]

Attention is currently required from: Raul Rangel, Aaron Durbin, Furquan Shaikh, Marshall Dawson, Julius Werner, Eric Peers.
Martin Roth has posted comments on this change. ( https://review.coreboot.org/c/coreboot/+/56048 )

Change subject: lib/future: Implement Futures API
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Patch Set 4:

(1 comment)

File src/lib/future.c:

https://review.coreboot.org/c/coreboot/+/56048/comment/513fac40_994a6bea 
PS2, Line 68: 		state = futures[i]->poll(futures[i], false);
> So I was tempted to add a bunch of debug style information in the the futures object. […]

I'll leave it up to you - i think it might be useful to print something when a task actually gets executed, but not when it just checks to see if anything needs to happen.  I'd be good with this happening later too, so we can actually decide whether or not it's needed.