title: gradle and C++ plugin using clang, include as system headers?
body: <p>Gradle can be used to compile C++ code. </p>
  
  <p>Of course, one can define dependencies on third party libraries, like boost, for example:</p>
  
  <pre><code>repositories {
    libs(PrebuiltLibraries) {
      boost_thread {
        binaries.withType(StaticLibraryBinary) {
          staticLibraryFile = file("third_party/boost/lib/libboost_system.a")
        }
        headers.srcDir "third_party/boost/include/"
      }
    }
  </code></pre>
  
  <p>From my understanding in terms of headers this is somewhat similar to inclusion by:</p>
  
  <pre><code>-Ithird_party/boost/include
  </code></pre>
  
  <p>However directories inclusion can also be achieved (at least in clang 3.4) by invoking:</p>
  
  <pre><code>-isystem third_party/boost/include
  </code></pre>
  
  <p>Benefit being silencing warnings in the headers files.</p>
  
  <p>And so the question is how to do this in gradle the right way? </p>
  
  <p>I figured I could omit the headers directories within libs(PrebuiltLibraries) section and manually add them to the compiler args, but this seems more of a workaround.</p>