Blender Git Loki

UI: Use paint crosshair cursor in all paint & sculpt modes

Currently, we use the crosshair cursor in Sculpt mode, but not in the other paint modes.

- Sculpt Mode: This crosshair cursor is too weighty.
- Texture, Weight, Vertex Paint: Using the arrow cursor for painting is not right.

This commit makes the following changes:

- Use the new special paint crosshair instead
- Use this cursor in all paint modes, not just Sculpt

Reviewed by: Brecht

Differential Revision: https://developer.blender.org/D5940