Currently, when compiling WITH_CYCLES, the CUDA dependency ends up being required, regardless of the WITH_CYCLES_CUDA_BINARIES option.
This patch makes it so that if both WITH_CYCLES_CUDA_BINARIES and WITH_CUDA_DYNLOAD are unchecked, CUDA will not be required.
- I am not entirely sure that I got the meaning of the options correct. If not, I can add an extra one that encompasses those two.
This patch saves some time for developers who don't have NVidia cards or don't want to install CUDA and all the proprietary drivers.