Blender Git Loki

Fix Sculpt tools showing the cursor of the previous active brush

When using a tool that is not a brush, the previously used brush
preset will still be active in the tool settings, so the cursor will
draw its custom reviews.
This checks if the current active tool is a brush before drawing its
previews. If it is not a brush tools, it draws a default white cursor.

Reviewed By: sergey

Differential Revision: https://developer.blender.org/D9418