title: Uninstalling opencv yet pkg-config still shows the version number
body: <p>I've searched similar topics but didn't solved my problem.
  I've uninstalled opencv-3.2.0 from source using:</p>
  
  <pre><code>sudo make uninstall
  </code></pre>
  
  <p>and I want to install opencv-3.3.1 but before i do that i wanted to make sure the previous version in completely gone.
  so i ran:</p>
  
  <pre><code>pkg-config --modversion opencv
  </code></pre>
  
  <p>and it returns</p>
  
  <pre><code>3.2.0
  </code></pre>
  
  <p>how do i make the system forget about 3.2.0 version, and move on?</p>