Miri is missing from releases since the introduction of smoke tests

[pietroalbini]

After #25 got merged Miri stopped shipping from releases. Miri is a bit special in the release process since we only ship it if the tests also pass, and to do so we rely on toolstates-linux.json. #25 changed the release process to be like this though:

1. ...
2. A manifest with dummy endpoints is generated (parsing toolstates-linux.json to decide whether to include Miri).
3. Files that are not included in the manifest are removed (removing toolstates-linux.json)
4. All files are hashed and signed.
5. Smoke tests are executed, installing the release through Rustup and trying to compile something.
6. A manifest with the production endpoints is generated (BUG! toolstate-linux.json was removed earlier).
7. The new manifest is hashed and signed.
8. ...

A possible solution is to move step 6 right after step 2, generating the two sets of manifests in different directories.

[RalfJung]

Another option might be to keep the JSON file around.

[pietroalbini]

Opened #31 with the solution I outlined in my earlier comment!

Another option might be to keep the JSON file around.

I kinda prefer reordering steps, to avoid making exceptions to the pruning code.

[pietroalbini]

Started a nightly release on the staging environment to make sure this is working. Will have results in less than an hour.

[pietroalbini]

@RalfJung confirmed the manifest now contains miri! You can test it yourself with:

RUSTUP_DIST_SERVER="https://dev-static.rust-lang.org" rustup update nightly