> My question is, is it possible for us to include (copy) those header files and
> distribute them inside package "qtbase5-private-dev" so that package
> "qt5dxcb-plugin" could build-dep on qtbase5-private-dev instead of bundling
> them inside repository (like what Fedora did)?
It ought to really work with what Qt ships, not trying to outsmart Qt
this way. Why does qt5dxcb-plugin need these headers? If it really
needs them (IMHO it should just use what Qt provides, even as private
headers), did you ask upstream Qt to provide them or the equivalent API
for what qt5dxcb-plugin wants to do?