CMake removes SDK/include/tbb

Created by: xrombik

Commit 182db49c0ff3308c3f2128574268d5b99978b088 should be removed from PR.

Originally posted by @drug007 in https://github.com/OpenXRay/xray-16/pull/312#issuecomment-450735753

These changes appear after running cmake in a Linux environment. Even if I roll back to the prev commit, these changes will still exist.