QtWayland configure failure for wayland_egl plug-in

Summary

During the do_configure task for QtWayland the config test fails for the plug-in wayland_egl. This results in the wayland-egl library not being built and therefore is not present in the rootfs either. As a result the GDP HMI launcher fails to start because of the missing files.

The missing files are:
/usr/lib/qt5/plugins/wayland-graphics-integration-client/libwayland-egl.so
/usr/lib/qt5/plugins/wayland-graphics-integration-server/libwayland-egl.so

Details

The yocto configure log (full log attached) reports the error:

   Checking for wayland_egl... no
   Checking for drm_egl_server... yes
   Project MESSAGE: no wayland-egl support detected, cross-toolkit compatibility disabled

The build directory config.log reports a slightly different error:

  Project ERROR: wayland-egl development package not found

This results in the build task not building the wayland_egl plug-in.

At runtime the GDP HMI Launcher fails with the systemd journal message :

Failed to load client buffer integration: wayland-egl

With the QT_DEBUG_PLUGINS environment variable set this becomes:

QFactoryLoader::QFactoryLoader() checking directory path "/opt/gdp-hmi/bin/wayland-graphics-integration-client" ...
Failed to load client buffer integration: wayland-egl

My working assumption is that this issue is exposed by the move in YP 2.3 (Pyro) to per recipe sysroot. I suspect that previously the missing dependency was available in the global sysroot and that is no longer the case.

The use of Qt 5.6 in GDP is perhaps also a complicating issue. I suspect that the Pyro upstream meta-qt5 layer uses a later version and so GDP does not use the pyro branch. As a result there may be issues such as this in the meta-qt5 branch being used where recipes have not been fully adopted to YP 2.3 (Pyro).