message: cuda timer doesn't need nvcc
diff: #ifndef VSNRAY_COMMON_TIMER_H
  #define VSNRAY_COMMON_TIMER_H 1
  +#include <common/config.h>
  +
  #include <chrono>
  -#ifdef __CUDACC__
  +#if VSNRAY_HAVE_CUDA
  #include <cuda_runtime_api.h>
  #endif
  @@ -50,7 +52,7 @@ private:
  };
  -#ifdef __CUDACC__
  +#if VSNRAY_HAVE_CUDA
  namespace cuda
  {
  @@ -157,7 +159,7 @@ private:
  using frame_counter = basic_frame_counter<timer>;
  -#ifdef __CUDACC__
  +#if VSNRAY_HAVE_CUDA
  namespace cuda
  {
  using frame_counter = basic_frame_counter<cuda::timer>;
  