d3dretrace: Add comment regarding IDXGISwapChainDWM::GetBuffer.
d3dretrace: Add comment regarding IDXGISwapChainDWM::GetBuffer.

schulmar/apitrace,swq0553/apitrace,tuanthng/apitrace,swq0553/apitrace,surround-io/apitrace,apitrace/apitrace,swq0553/apitrace,joshua5201/apitrace,surround-io/apitrace,EoD/apitrace,schulmar/apitrace,surround-io/apitrace,trtt/apitrace,trtt/apitrace,swq0553/apitrace,apitrace/apitrace,apitrace/apitrace,surround-io/apitrace,EoD/apitrace,joshua5201/apitrace,schulmar/apitrace,EoD/apitrace,schulmar/apitrace,EoD/apitrace,joshua5201/apitrace,joshua5201/apitrace,tuanthng/apitrace,tuanthng/apitrace,schulmar/apitrace,tuanthng/apitrace,joshua5201/apitrace,surround-io/apitrace,tuanthng/apitrace,apitrace/apitrace,EoD/apitrace,swq0553/apitrace,trtt/apitrace,trtt/apitrace,trtt/apitrace