message: Fix -Wunused-but-set-variable.
  Cr-Commit-Position: refs/heads/main@{#35282}
diff: @@ -60,7 +60,6 @@ IPin* GetInputPin(IBaseFilter* filter) {
  }
  IPin* GetOutputPin(IBaseFilter* filter, REFGUID Category) {
  - HRESULT hr;
  IPin* pin = NULL;
  IEnumPins* pPinEnum = NULL;
  filter->EnumPins(&pPinEnum);
  @@ -68,7 +67,7 @@ IPin* GetOutputPin(IBaseFilter* filter, REFGUID Category) {
  return NULL;
  }
  // get first unconnected pin
  - hr = pPinEnum->Reset(); // set to first pin
  + pPinEnum->Reset(); // set to first pin
  while (S_OK == pPinEnum->Next(1, &pin, NULL)) {
  PIN_DIRECTION pPinDir;
  pin->QueryDirection(&pPinDir);
  