title: Create a recipe for a QT5 application
body: <p>I have been struggling for too long, so I need help :)</p>
  
  <p>I made a big QT5.8 application and usually when I want to compile it with my PC I just have to run the following command: qmake -qt=5.9  -spec linux-arm-gnueabihf-g++ -config configuration_name.
  With this command, I can  cross compile my source code for the armhf architecture using linux-arm-gnueabihf-g++ toolchain.</p>
  
  <p>But now, as can easily create a yocto image for my target (Raspberry pi), I want to make a recipe in order to compile my qt software and put it into my image.
  For now, I achieved to perform these following task in my recipe without errors:</p>
  
  <ul>
  <li><strong>do_fetch</strong> -> Yocto fetch the source from git repo (OK)</li>
  <li><strong>do_unpack</strong> -> OK</li>
  </ul>
  
  <p>After that I want to perform a qmake command in order to generate my makefile, but here is my problem :/</p>
  
  <p>First, I included the qmake5 class in my recipe using </p>
  
  <pre><code>require recipes-qt/qt5/qt5.inc
  </code></pre>
  
  <p>Then I tried a lot of things..</p>
  
  <p>writing "qmake" into the <strong>do_configure</strong> task doesn't work. Last thing I tried was: '${OE_QMAKE_QMAKE} ${S}/my_software.pro -config my_config' but still the same error:</p>
  
  <pre><code>Could not find qmake spec 'linux-oe-g++'
  </code></pre>
  
  <p>I don't know what to do and I can't find any recipe exemple doing the things that I want to do.
  If somebody already experienced this issue or have experience compiling qt5 software with a yocto recipe I would like your help :)</p>
  
  <p>my recipe:</p>
  
  <pre><code>LICENSE = "CLOSED"
  LIC_FILES_CHKSUM = " "
  USERNAME = "****"
  PASSWORD = "*****"
  S = "${WORKDIR}/git"
  
  require recipes-qt/qt5/qt5.inc
  
  do_fetch(){
  git clone http://${USERNAME}:${PASSWORD}@gitlab.....  
  }
  
  do_configure () {
  ${OE_QMAKE_QMAKE} ${S}/my_software.pro -config my_config
  }
  </code></pre>
  
  <p>Thanks</p>