[RFC] wined3d: Avoid triggering OPENGL errors when setting point size

[Vincent Pelletier]

(Resent, originally sent to -patches... Sorry)

If WINED3DRS_POINTSCALEENABLE is false and WINED3DRS_POINTSIZE render state is 
set to an invalid size, glPointSize will fail.
This happens in "Black & White 2", causing log/stderr to be flooded with 
opengl errors.

I'm not sure if this should be fixed here, or when setting state value.
Also, maybe it should be avoided to double-check against opengl bounds when 
WINED3DRS_POINTSCALEENABLE is true.

I would be happy to get some feedback on that patch.