Blender Git Loki

GPencil: Fix unreported visual problem for short strokes

When the stroke has less than 3 points, but only the fill material is enabled, the stroke is invisible and makes the shaders to remove any fill because the shader start and end pointers are not correct.

Now, if the stroke has only fill, but it is not fillable, it is drawn with the stroke color to avoid the errors and these ghost strokes.