try to make the Windows CI not rebuild Miri

[RalfJung]

No description provided.

[RalfJung]

Odd, seems like we are entirely starved for CI runners, both Travis and AppVeyor? Cc @rust-lang/infra

[pietroalbini]

Yep, all the queues are filled.

[RalfJung]

Dang, that did not help. Cargo still is not doing the same feature resolution for the release build and the install job, but only on Windows. (Cc rust-lang/cargo#6983 and @ehuss, but I don't think this is worth deep investigation.)

Still, this change makes things more consistent with Travis, so I still think it is a good idea.

[ehuss]

Yea, you'll need to do the same investigation, this time with winapi, to see which additional features are enabled. Unfortunately winapi has dozens of features, and the set will probably change over time, so it will probably be more trouble than it's worth.

[RalfJung]

That rebuild is almost 20% of our Windows CI time. But yeah, without even having a Windows machine I am not going to attempt this.^^

[shepmaster]

without even having a Windows machine

Microsoft offers free (time-limited) VMs which I use successfully for answering Windows-related Rust questions