use `StorageLive` and `StorageDead` to allocate/deallocate stack memory

[oli-obk]

I haven't read up on them, but the way they are sprayed around in MIR looks very much like that is how they would work.

[jonas-schievink]

Note that rust-lang/rust#38669 might cause issues

[oli-obk]

yea I already ran into this but failed to fix it in rustc.

[oli-obk]

related: rust-lang/rust#39409

[RalfJung]

So @nikomatsakis suggested I work on this as a way to make myself familiar with miri. It seems nobody has started tackling this issue yet, so hopefully there won't be any collisions.

[oli-obk]

Great! It's all yours