Bug with rasterize camera transforms and transparent objects

[Frank C. <dev...@ch...>]

When using a rasterize camera transform, any transparent triangles with 
Z coordinates other than 0 aren't drawn. The problem lies in 
ir_geom_transparent_add, where triangles "behind" the camera are culled 
- this doesn't seem to work with rasterize transforms, probably because 
Z is inverted.

I haven't looked into the problem further, but disabling the culling 
altogether restores the expected behaviour (at the cost over possible 
overdraw).

Frank.