message: we don't deallocate the environ global, so leave it in the machine
diff: @@ -55,7 +55,7 @@ impl<'tcx> EnvVars<'tcx> {
  ecx.memory.deallocate(ptr, None, MiriMemoryKind::Env.into())?;
  }
  // Deallocate environ var list.
  - let environ = ecx.machine.env_vars.environ.take().unwrap();
  + let environ = ecx.machine.env_vars.environ.unwrap();
  let old_vars_ptr = ecx.read_scalar(environ.into())?.not_undef()?;
  ecx.memory.deallocate(ecx.force_ptr(old_vars_ptr)?, None, MiriMemoryKind::Env.into())?;
  Ok(())
  