Include compiler crashes in ICE defintion

[Alexendoo]

This matches the definition used in glacier, which includes exit status
101 without an accompanying diagnostic (such as rust-lang/rust#21599), and when
rustc is killed by a signal (rust-lang/rust#13368)

This also means no processing modes are capturing stdio, but I didn't
remove it as it may be desired for the regex features discussed in #53

[pnkfelix]

I don't think this PR was quite right; it treats error code 101 as a unique identifier for ICE's, but even normal static errors from rustc cargo (driving rustc) will produce that same error code, I believe.

This mistake ends up breaking certain uses of --regress=ice, such as one I'm trying to include in my test suite as part of PR #88.

I'm going to revert this PR as part of PR #88 and open an issue to re-add its effects in a manner compatible with --regress=ice

[pnkfelix]

I do see that Glacier is using this same logic (link taken from commit). So either I'm wrong or glacier is wrong. Hmm.

[pnkfelix]

Ah, Glacier invokes rustc directly. So maybe Glacier's logic is correct for direct rustc invocations, but not appropriate for cargo invocations?

Update: Yes, experimentation indicates that is what is going on.

[Alexendoo]

Ah yeah sorry I didn't test cargo directly, I was using it with --script rustc -- file and assumed it would be the same