Builds fine now with Qt and QtWebEngine 5.6.2 (with -DENABLE_QWEBENGINE=ON), previously there were compiler errors like this:
```
/home/abuild/rpmbuild/BUILD/digikam-6.1.0/core/libs/dplugins/webservices/webwidget_qwebengine.cpp:54:50: error: 'WebGLEnabled' is not a member of 'QWebEngineSettings'
settings()->setAttribute(QWebEngineSettings::WebGLEnabled, false);
^~~~~~~~~~~~
/home/abuild/rpmbuild/BUILD/digikam-6.1.0/core/libs/dplugins/webservices/webwidget_qwebengine.cpp:55:50: error: 'Accelerated2dCanvasEnabled' is not a member of 'QWebEngineSettings'
settings()->setAttribute(QWebEngineSettings::Accelerated2dCanvasEnabled, false);
^~~~~~~~~~~~~~~~~~~~~~~~~~
```
Still builds fine with later versions, and/or without -DENABLE_QWEBENGINE=ON.