message: hack to make xargo libstd build work again
diff: #!/bin/sh
  cd "$(dirname "$0")"
  +sed 's/gcc = "0\.3\.50"/gcc = "=0\.3\.50"/' -i ~/.rustup/toolchains/*/lib/rustlib/src/rust/src/libstd/Cargo.toml
  RUSTFLAGS='-Zalways-encode-mir -Zmir-emit-validate=1' xargo build
  