title: make install: pkg-config does not find installed library
body: <p>I cross-compiled successfully an application from sources (Qt5 on Debian). When I type <code>make install</code> it returns this error:</p>
  
  <blockquote>
    <p>Updating projects from gyp files...
    Package dbus-1 was not found in the pkg-config search path.
    Perhaps you should add the directory containing `dbus-1.pc'
    to the PKG_CONFIG_PATH environment variable
    No package 'dbus-1' found</p>
  </blockquote>
  
  <p>But:</p>
  
  <pre><code>pkg-config --modversion dbus-1
  1.10.8
  pkg-config --libs dbus-1
  -ldbus-1
  </code></pre>
  
  <p>So it actually finds the <code>dbus-1</code> library.
  Furthermore:</p>
  
  <pre><code>echo $PKG_CONFIG_PATH
  /home/mark/opt/sysroot/usr/lib/pkgconfig/:/home/mark/opt/sysroot/usr/lib/arm-linux-gnueabihf/pkgconfig
  </code></pre>
  
  <p>shows the package is on the sysroot side (target architecture).
  What does this error really mean?</p>