In weightpaint it is possible to enable the bone selection mode. During
drawing the overlay was rendered, but during selection this was ignored.
Users needed to double click in order to select bones even when the overlay
was enabled.
This patch makes bone selection possible during weight painting using the pose mode bone
selection overlay with a single click.
Reviewed By: fclem, campbellbarton
Differential Revision: https://developer.blender.org/D5629
fc99297411