message: Add comments for trap::codegen_print gv and fn defs
diff: @@ -7,17 +7,19 @@ fn codegen_print(fx: &mut FunctionCx<'_, '_, impl cranelift_module::Backend>, ms
  returns: vec![],
  }).unwrap();
  let puts = fx.module.declare_func_in_func(puts, &mut fx.bcx.func);
  + fx.add_entity_comment(puts, "puts");
  let symbol_name = fx.tcx.symbol_name(fx.instance);
  - let msg_bytes = format!("trap at {:?} ({}): {}\0", fx.instance, symbol_name, msg).into_bytes().into_boxed_slice();
  + let real_msg = format!("trap at {:?} ({}): {}\0", fx.instance, symbol_name, msg);
  let mut data_ctx = DataContext::new();
  - data_ctx.define(msg_bytes);
  + data_ctx.define(real_msg.as_bytes().to_vec().into_boxed_slice());
  let msg_id = fx.module.declare_data(&(symbol_name.as_str().to_string() + msg), Linkage::Local, false, None).unwrap();
  // Ignore DuplicateDefinition error, as the data will be the same
  let _ = fx.module.define_data(msg_id, &data_ctx);
  let local_msg_id = fx.module.declare_data_in_func(msg_id, fx.bcx.func);
  + fx.add_entity_comment(local_msg_id, msg);
  let msg_ptr = fx.bcx.ins().global_value(pointer_ty(fx.tcx), local_msg_id);
  fx.bcx.ins().call(puts, &[msg_ptr]);
  }
  