qt3d examples require rhi plugin on Android

When running some qt3d examples like planets-qml (qt3d build from Conan), the app fails to find the rhi renderer and crashes

Abort message: 'Unable to find renderer plugin for rhi

A workaround is to explicitly set the renderer to opengl

qputenv("QT3D_RENDERER", "opengl");

Now, I'm not sure if the rhi renderer is not supported on Android, or whether qt3d build needs some extra flags for it to build the rhi renderer as well.