title: How to execute a library's Makefile from qmake
body: <p>I have a Qt project and a subfolder <code>libparanoia</code> that has it's own Makefile (few <code>.mk</code>'s) and a RULES/conf folder.
  When I execute <code>make</code> in the <code>libparanoia</code> folder it generates the <code>.o</code> files in a subfolder.</p>
  
  <p>How can I, when I build my Qt application, run the makefile from <code>libparanoia</code> (a subfolder in the Qt project folder) and add the <code>.o</code> library to my Qt project (ok that's <code>LIBS+=</code>)?</p>