Function cyclic_pick_cpu

* cyclic_pick_cpu will attempt to pick a CPU according to the constraints * specified by the partition, bound CPU, and flags. Additionally, * cyclic_pick_cpu() will not pick the avoid CPU; it will return NULL if * the avoid CPU is the only CPU which satisfies the constraints. * * If CYF_CPU_BOUND is set in flags, the specified CPU must be non-NULL. * If CYF_PART_BOUND is set in flags, the s