hey OSX-devs: we need to find a better solution for this things. I didn't notice the review before it was pushed, but I would not have given a shipit for it.
The solution is sementically wrong. We are now binding finding XCB to whehter XLib is found. In the long termn XLib support will become a deprecated feature, maybe even completely removed in KWindowSystem. Most is already ported to XCB. What then? We go back to finding XCB and it will be found again? Then there is nothing to group with.
Please think about a long term strategy how you want to handle the X11 dependencies. We have had many such reviews lately and it's always a local "workaround"/"fixup" to some OSX build-oddities. Please have a look at the bigger picture and think about a general solution on how to disable X11 without having to (stupidly) patch all frameworks.