iotests.py: tiny refactor: move system imports up

import string

import unittest

import sys

sys.path.append(os.path.join(os.path.dirname(__file__), '..', '..', 'scripts'))

import qtest

import struct

import json

import signal

import logging

sys.path.append(os.path.join(os.path.dirname(__file__), '..', '..', 'scripts'))

import qtest

# This will not work if arguments contain spaces but is necessary if we

# want to support the override options that ./check supports.