title: Unable to add defines to boost build
body: <p>I am trying to build a debug build of boost serialization/filesystem/system using boost buildsystem. Here is what I use:</p>
  
  <pre><code>  b2 serialization filesystem system variant=debug link=static threading=multi
    runtimelink=static define=_HAS_ITERATOR_DEBUGGING=0 toolset=msvc-11.0
  </code></pre>
  
  <p>However, when I include the library in my debug visual studio projects I still get errors like this:</p>
  
  <pre><code>(basic_iarchive.obj) : error LNK2038: mismatch detected for '_ITERATOR_DEBUG_LEVEL': value '2' doesn't match value '0' in Game.obj
  </code></pre>
  
  <p>Which leads me to belive that my 'define' in the boost build did not have any effect. What is the proper syntax? I cannot find any examples, and the documentation dosnt say anything else on the matter.</p>
  
  <p>EDIT: I would like to enforce that I want to define _HAS_ITERATOR_DEBUGGING=0 in my boost build</p>