title: How to specify Mac platform in qmake (QtCreator)
body: <p>I would like to set some configurations for Mac OS in <code>pro</code> file via QtCreator. I read the document, and found it supports Windows and Unix, like the following, </p>
  
  <pre><code> win32 {
       SOURCES += hellowin.cpp
   }
   unix {
       SOURCES += hellounix.cpp
   }
  </code></pre>
  
  <p>I understand Mac OS is *nix-like OS, however, I still want to make difference with Linux. Is there a way to do this?</p>
  
  <hr>
  
  <p>Ubuntu + Qt5.1</p>