[Interest] private header paths and cmake

[René J. V. Bertin]

Thiago Macieira wrote:

> Those are internal_modules. Since they are meant to be used only by Qt itself
> and Qt builds itself using qmake, there are no CMake files.

I thought it might be something like that. Can one at least be certain that the 
headers are normally installed under QT_INSTALL_HEADERS and the libraries in 
QT_INSTALL_LIBS, and my approach below should thus work not just on my own 
system?

https://github.com/RJVB/osx-integration/commit/1fd486c7c57fe047ae30b28bb14c4dd988998b74

Thanks,
R.