chore: import upstream snapshot with attribution

csrc/utils.cpp

@@ -0,0 +1,13 @@
+#include <cuda_runtime.h>
+#include <stdexcept>
+#include "utils.h"
+
+std::string get_gpu_pci_bus_id(int device) {
+  char pciBusId[13];  // 13 bytes per CUDA doc
+  cudaError_t err = cudaDeviceGetPCIBusId(pciBusId, sizeof(pciBusId), device);
+  if (err != cudaSuccess) {
+    throw std::runtime_error(std::string("cudaDeviceGetPCIBusId failed: ") +
+                             cudaGetErrorString(err));
+  }
+  return std::string(pciBusId);
+}