message: avoid env var forwarding logic panicking for non-UTF-8 env vars
diff: @@ -50,10 +50,10 @@ impl<'tcx> EnvVars<'tcx> {
  // Skip the loop entirely if we don't want to forward anything.
  if ecx.machine.communicate() || !forwarded_env_vars.is_empty() {
  - for (name, value) in env::vars() {
  + for (name, value) in env::vars_os() {
  let forward = match ecx.machine.communicate() {
  - true => !excluded_env_vars.contains(&name),
  - false => forwarded_env_vars.contains(&name),
  + true => !excluded_env_vars.iter().any(|v| v.as_str() == &name),
  + false => forwarded_env_vars.iter().any(|v| v.as_str() == &name),
  };
  if forward {
  let var_ptr = match target_os {
  