Investigation based on comments on:

https://gerrit.automotivelinux.org/gerrit/c/AGL/meta-agl-demo/+/22000

show that our specification of qtbase in recipe DEPENDS is inconsistent.  The cmake_qt5 bbclass adds it automatically, but the qmake5 bbclass used by many recipes does not.  Those recipes currently build because qtbase is pulled in as a second order dependency by other things in DEPENDS.  To ensure robustness and be consistent with qmake5 usage in meta-qt5, affected recipes should have qtbase added to their DEPENDS.