message: Add a known panic case
diff: @@ -32,22 +32,40 @@ $ ./build.sh
  ## Not yet supported
  -* [ ] Checked binops
  -* [ ] Statics
  -* [ ] Drop glue
  +* Checked binops
  +* Statics
  +* Drop glue
  -* [ ] Building libraries
  -* [ ] Other call abi's
  -* [ ] Unsized types
  -* [ ] Slice indexing
  -* [ ] Sub slice
  -* [ ] Closures
  -* [ ] Some rvalue's
  +* Building libraries
  +* Other call abi's
  +* Unsized types
  +* Slice indexing
  +* Sub slice
  +* Closures
  +* Some rvalue's
  -* [ ] Inline assembly
  -* [ ] Custom sections
  +* Inline assembly
  +* Custom sections
  ## Known errors
  -* [ ] cranelift-module api seems to be used wrong, thus causing panic for some consts
  -* [ ] cranelift-codegen doesn't have encodings for some instructions for types smaller than I32
  +* cranelift-module api seems to be used wrong, thus causing panic for some consts
  +* cranelift-codegen doesn't have encodings for some instructions for types smaller than I32
  +
  +```
  +[...]
  +warning: DefId(0/0:128 ~ lib[8787]::f64[0]::{{impl}}[0]::classify[0]):
  +fn f64::<impl at ./target/libcore/src/libcore/num/f64.rs:156:1: 490:2>::classify(_1: f64) -> num::FpCategory{
  +[...]
  +}
  +warning: stmt _3 = _1
  +warning: stmt _5 = BitAnd(move _6, const Unevaluated(DefId(0/0:130 ~ lib[8787]::f64[0]::{{impl}}[0]::classify[0]::MAN_MASK[0]), []):u64)
  +thread 'main' panicked at 'called `Option::unwrap()` on a `None` value', libcore/option.rs:345:21
  +stack backtrace:
  +[...]
  + 10: <core::option::Option<T>>::unwrap
  + at /checkout/src/libcore/macros.rs:20
  + 11: rustc_codegen_cranelift::constant::trans_constant
  + at src/constant.rs:26
  +[...]
  +```
  