I just found out CL_DEVICE_TOPOLOGY_AMD does not work with the latest AMD drivers.
This explains why GGS cannot detect GPU's properly with these drivers. Grrrrr...
The newest drivers are using the HSA/ROCm compiler, which is no longer targeted specifically at GPUs.
I suggest using -legacy at least as an interim solution.
See, the thing is, I need to get information about device topology before the program is built.
clGetDeviceInfo() is broken, and AMD people really have to get their act together and fix this issue.