if anyone *actually* knows how to tell a complex cmake project to just shove an extra include directory into everything so it can find the Boost headers properly, please let me know.

needs to be done from the cmake command invocation because this project has literally hundreds of cmakelists and they're complicated as hell and I refuse to spend hours mucking about with them.

I've tried `CXXFLAGS="-I ..." cmake .` and it made no difference.