title: How to specify target mac os x version using qmake
body: <p>I am trying to compile c++11 code on the Mac OS X using Qt Creator/qmake and I am getting the following error:</p>
  
  <pre><code>clang: error: invalid deployment target for -stdlib=libc++ (requires OS X 10.7 or later)
  </code></pre>
  
  <p>When I checked the compile command line, I noticed that it contains the -mmacosx-version-min=10.6 flag. I tried to update my .pro file as follows, but it seems that this is not taken into account:</p>
  
  <pre><code>QMAKE_CXXFLAGS += -std=c++11 -stdlib=libc++
  
  macx {
      -mmacosx-version-min=10.7
  }
  </code></pre>
  
  <p>Any suggestions would be helpful. Thanks!</p>