rework _pscthr_begin() thread allocation - self build works.
rework _pscthr_begin() thread allocation - self build works.

pscedu/pfl,pscedu/slash2-stable,pscedu/pfl,pscedu/pfl,pscedu/slash2-stable,pscedu/slash2-stable,pscedu/slash2-stable,pscedu/slash2-stable,pscedu/pfl,pscedu/slash2-stable,pscedu/slash2-stable