Final fixes for Mac OSX/CLang build:

- Removed toolchain selection for Mac OSX: use default compiler - `clang`
- Add `X11` libs and headers dependency for `lsd_slam_core` library target
- Correct const parameter in `trackingFailed` multi-map in `Frame.h`
- Removed `std::vector` parameter `Eigen::aligned_allocator<FramePoseStruct*>`,
  it seems to be unused appendix, but still breakes build due to being of different
  type than first argument, and clang is strict in this case.