Patch by Andrey Churbanov
Taskloop implementation is extended by using recursive task scheduling.
Envirable KMP_TASKLOOP_MIN_TASKS added as a manual threshold for the user to switch from recursive to linear tasks scheduling.
- The calculations for the loop parameters are moved from __kmp_taskloop_linear upper level
- Initial calculation is done in the __kmpc_taskloop, further range splitting is done in the __kmp_taskloop_recur.
- Added threshold to switch from recursive to linear tasks scheduling;
- One half of split range is scheduled as an internal task which just moves sub-range parameters to the stealing thread that continues recursive scheduling (if number of tasks still enough), the other half is processed recursively;
- Internal task duplication routine fixed to assign parent task, that was not needed when all tasks were scheduled by same thread, but is needed now.