title: antcall target="release" breaks with google-play-services_lib
body: <p>I am trying to build my android apps from command line, I have a script</p>
  
  <p><code>ant release</code></p>
  
  <p>fails at </p>
  
  <pre><code>BUILD FAILED
  android-sdk-macosx/tools/ant/build.xml:473: Invalid file: myProject/google-play-services_lib/build.xml
  </code></pre>
  
  <p>this is necessary for the android google maps v2 api </p>
  
  <p>I tried to add my other build.xml to the <code>google-play-services_lib</code> but then it didn't recognize my directories particualr the variables <code>sdk.dir</code></p>
  
  <p>how do I fix this and add this library to my ant build?</p>