message: Fix -Wunused-but-set-variable.
  This is part of a set of CLs to fix the Chromium roll.
  Cr-Commit-Position: refs/heads/main@{#35286}
diff: @@ -30,7 +30,6 @@ LONGLONG GetMaxOfFrameArray(LONGLONG* maxFps, long size) {
  }
  IPin* GetInputPin(IBaseFilter* filter) {
  - HRESULT hr;
  IPin* pin = NULL;
  IEnumPins* pPinEnum = NULL;
  filter->EnumPins(&pPinEnum);
  @@ -39,7 +38,7 @@ IPin* GetInputPin(IBaseFilter* filter) {
  }
  // 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;
  