fix for compiling the new lightmapper

[Valentactive]

also changed a call in scene/3d/baked_lightmap.cpp that was ambiguous

Here the build error before:

[akien-mga]

Looks good, but @bruvzg had another error on macOS, could you fix it too?

scene/3d/voxel_light_baker.cpp:1032:15: error: call to 'pow' is ambiguous
                float att = Math::pow(1.0 - angle / p_spot_angle, p_spot_attenuation);
                            ^~~~~~~~~

(should also be 1.0f)

[akien-mga]

Please squash the two commits together.