message: Some changes to Readme.md
  `rustup override set nightly` is not needed, because there is a `rust-toolchain` file.
  cc
diff: @@ -22,7 +22,7 @@ $ rustc -Zcodegen-backend=$(pwd)/target/debug/librustc_codegen_cranelift.so my_c
  ## Build sysroot and test
  ```bash
  -$ rustup component add rust-src # Make sure the sysroot source is availablr
  +$ rustup component add rust-src # Make sure the sysroot source is available
  $ ./prepare_libcore.sh # Patch the sysroot source for some not yet supported things
  $ ./build.sh
  ```
  @@ -36,3 +36,13 @@ $ ./build.sh
  * libstd (needs varargs and some other stuff) ([tracked here](https://github.com/bjorn3/rustc_codegen_cranelift/issues/146))
  * u128 and i128 ([no cranelift support](https://github.com/CraneStation/cranelift/issues/354))
  * SIMD (huge amount of work to get all intrinsics implemented, so may never be supported)
  +
  +## Troubleshooting
  +
  +### Can't compile
  +
  +Try updating your nightly compiler. You can try to use an nightly a day or two older if updating rustc doesn't fix it. If you still can't compile it, please fill an issue.
  +
  +### error[E0463]: can't find crate for `std` while compiling a no_std crate
  +
  +If you use `RUSTFLAGS` to pass `-Zcodegen-backend` to rustc, cargo will compile `build-dependencies` with those flags too. Because this project doesn't support libstd yet, that will result in an error. I don't know of any way to fix this. :(
  