* apply openmp simd
* clean __buildin detection, moving windows build check from xgboost project, add openmp support for vectorize reduce
* apply openmp only to rabit
* orgnize rabit signature
* remove is_bootstrap, use load_checkpoint as implict flag
* visual studio don't support latest openmp
* orgnize omp declarations
* replace memory copy with vector cast
* Revert "replace memory copy with vector cast"
This reverts commit 28de4792dcdff40d83d458510d23b7ef0b191d79.
* Revert "orgnize omp declarations"
This reverts commit 31341233d31ce93ccf34d700262b1f3f6690bbfe.
* remove openmp settings, merge into a upcoming pr
* mis
* per feedback, update comments
9a7ac85d7e