message: Update documentation for getCudaEnabledDeviceCount
  Inform users that getCudaEnabledDeviceCount can return -1 in some cases.
diff: @@ -595,7 +595,8 @@ private:
  /** @brief Returns the number of installed CUDA-enabled devices.
  Use this function before any other CUDA functions calls. If OpenCV is compiled without CUDA support,
  -this function returns 0.
  +this function returns 0. If the CUDA driver is not installed, or is incompatible, this function
  +returns -1.
  */
  CV_EXPORTS int getCudaEnabledDeviceCount();
  