Building kitinerary in the PIM docker

[Glen Ditchfield]

I'm trying to build kitinerary master with the PIM docker image, but the 
build fails.  The error.log file ends with this:
===========
-- Configuring done
CMake Error at src/lib/CMakeLists.txt:7 (add_library):
  Target "KPimItinerary" links to target "Qt5::QmlPrivate" but the 
target was
  not found.  Perhaps a find_package() call is missing for an IMPORTED
  target, or an ALIAS target is missing?
===========

What's missing?