Blender Git Loki

Performance: Flush selection to edges/faces.

This patch uses threading to flush selection from verts to edges and
from edges to faces. The solution is lockless and should scale well on
modern CPU architectures.

Master:{F10185359}
Patch:{F10185361}

End user performance went from 3.9 to 4.6 FPS (Stanford Dragon) but that
was measured on a Intel Core i7-6700 CPU and AMD RX480 Gpu. The more
cores the better improvements you get.

Reviewed By: mano-wii

Differential Revision: https://developer.blender.org/D11644