Added --expt-relaxed-constexpr to NVCC flags for CMake to enable using std::abs inside device code.
Added --expt-relaxed-constexpr to NVCC flags for CMake to enable using std::abs inside device code.

gpuopenanalytics/libgdf,gpuopenanalytics/libgdf,gpuopenanalytics/libgdf,gpuopenanalytics/libgdf