Thanks to juston_li on the NVIDIA forums, there is now a patch to fix the compile error with Kernel 4.3-rc1.
Details – and the patch – can be found here: https://devtalk.nvidia.com/default/topic/877365/linux/355-11-linux-4-3-rc1-build-error/
I have applied this, and the NVIDIA driver now compiles and installs OK (as the GPL_Only error was fixed in 4.3-rc1).
Now to attempt to use the same logic on the (similar) VMware error!
Robert Gadsdon. September 12. 2015.