cocos2D-X call JNIHelper

#ifndef _WIN32
    JNIEnv *j = JniHelper::getEnv();
    if (j == nullptr || j == NULL)
    {test += "JNIEnv == NULL";}
    else
    {
        jstring js = j->NewStringUTF(std::string(" new string utf ").c_str());
        std::string j2s = JniHelper::jstring2string(js);
        test += j2s;
    }
#endif