title: Why Qt plaftorm plugin "xcb" cannot be loaded even though it was found?
body: <p>I cross-compiled Qt5.12 in my laptop and installed it on a Raspberry Pi 3 that runs Raspbian Stretch OS. I'm trying to remote debug (from QtCreator) applications running on RPi.</p>
  
  <p>When I run my Qt apps from RPi terminal with a command like <code>./app -platform xcb</code> it works fine, but when I try to run the same app from a remote debug session I get the following output:</p>
  
  <pre><code>Could not load shared library symbols for /usr/local/qt5pi/plugins/platforms/libqxcb.so.
  Do you need "set solib-search-path" or "set sysroot"?qt.qpa.xcb: could not connect to display 
  qt.qpa.xcb: could not connect to display 
  qt.qpa.plugin: Could not load the Qt platform plugin "xcb" in "/usr/local/qt5pi/plugins/platforms" even though it was found.
  This application failed to start because no Qt platform plugin could be initialized. Reinstalling the application may fix this problem.
  
  Available platform plugins are: 
  eglfs (from /usr/local/qt5pi/plugins/platforms), 
  linuxfb (from /usr/local/qt5pi/plugins/platforms), 
  minimal (from /usr/local/qt5pi/plugins/platforms), 
  minimalegl (from /usr/local/qt5pi/plugins/platforms), 
  offscreen (from /usr/local/qt5pi/plugins/platforms), 
  vnc (from /usr/local/qt5pi/plugins/platforms), 
  webgl (from /usr/local/qt5pi/plugins/platforms), 
  xcb (from /usr/local/qt5pi/plugins/platforms), 
  eglfs, linuxfb, minimal, minimalegl, offscreen, vnc, webgl, xcb.
  </code></pre>
  
  <p>Has anyone ever experienced this? What could I try to fix that?</p>