Light-linking on geometry lights not working correctly

[sebastienblor]

The attached scene has a geometry light and light-linking, but the light linking doesn't seem to be applied properly
geomLights.zip

[autodesk-oss-arnold-bot]

Issue synced internally to ARNOLD-13650

[xsisupport]

Here's another Houdini scene that shows another asapect of the light linking problems with geometry lights.
As soon as you use light linking on some other light, the geometry light stops working.
geometry_light_light_linking.zip

The HDDEBUG ass file shows that the geometry light is not added to the polymesh light_groups.
Like this:

`
polymesh
{
name /sphere1

use_light_group on
light_group 2 1 NODE
"/lights/arealight1" "/lights/arealight_yellow"

}

mesh_light
{
name /sphere1/light
color 0 0 1
exposure 12
mesh "/sphere1"
}
`