So the actual issue is:
make[2]: *** No rule to make target `/usr/local/cuda/lib64/libculibos.a', needed by `run_pytorch'.  Stop.

not the earlier one. The earlier one was because I wrote …/cudnn…/lib instead of …/cudnn…/lib64.
I note that even if I append the absolute location of libculibos.a (which isn’t in /usr/local/cuda/lib64) to CMakeLists.txt in target_link_libraries, I see the same error. I have no idea why it thinks any of my cuda libraries are in /usr/local/cuda/lib64 as this directory does not exist.