Profile only the kernels involved in the benchmark

[fbusato]

NVBench currently allows kernel profiling with external tools with the flag --profile. On the other hand, profiling tools collect all activities in the benchmark, including "setup/initialization" kernels that are not part of the section under evaluation. NVBench should add cudaProfilerStart() and cudaProfilerStop() in profiling mode (--profile).

CUDA Runtime API reference