Document that gccrs does not try to replicate internal compiler errors

[DemiMarie]

ICEs are a part of rustc’s behavior that gccrs should not try to replicate.

[liamnaddell]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=114629

[DemiMarie]

I’m not a Rust developer, but I don’t think Easter eggs should be considered normative behavior.

[powerboat9]

I think it should be very low priority to match rustc Easter eggs, but I find the rational for removing already implemented Easter eggs (as long as they're consistent with rustc) to be rather subjective, stuffy, and uncompelling.

[DemiMarie]

That’s fair. What I meant is the broader point that if rustc ICEs and gccrs doesn’t ICE, that is not a gccrs bug in general.