The script ignores Compute v2.1

[Maghoumi]

There is a problem with cuda_compute_capability.c. It is caused by:

    if (major == 2 && minor == 1)
    {
        // There is no --arch compute_21 flag for nvcc, so force minor to 0
        minor = 0;
    }

See, the problem is that some Fermi cards do support Compute v2.1. In fact, Compute v2.1 exists (see https://en.wikipedia.org/wiki/CUDA#Supported_GPUs) but the way to activate that would be through setting the flags as -arch compute_20 -code sm_21.

The script currently assumes that whatever compute_xx is, sm should be also followed by the same number and be set as sm_xx. I've ran into problems with sm_20 on a machine that supports sm_21 before. For instance, I vaguely recall that numerical computations were more accurate with sm_21 than sm_20 (on the Caffe library if I recall). Considering the large number of CMake scripts out there that rely on this script, I hope the issue is fixed :)

Unfortunately, my knowledge about CMake is rather limited, otherwise I would've fixed it and submitted a pull request.