title: Error base operand of '->' has non-pointer type 'JNIEnv {aka _JNIEnv}' when create NDK project
body: <p>I create my first NDK project, that show some text on screen.
  I use native method in class NativeLib in java and implement in a class in C.
  But I received an error base operand of '->' has non-pointer type 'JNIEnv {aka _JNIEnv}</p>
  
  <pre><code> #include &lt;jni.h&gt;
   #include &lt;string.h&gt;
   #include &lt;stdio.h&gt;
   #include &lt;android/log.h&gt;
  
  #define DEBUG_TAG "MY_NDK_DEMO"
  JNIEXPORT jstring JNICALL Java_com_example_helloworld_NativeLib_helloWorld
    (JNIEnv * env, jobject obj) {
      return (*env)-&gt;NewStringUTF("Hello World JNI!");
  }
  </code></pre>