Fix memory leak in QWindowsAudioDeviceInfo::availableDevices().

Task-number: QTBUG-44305
Change-Id: I8c5afd6d5c77ef1ef81c3b752c6246dc50406794
Reviewed-by: Yoann Lopes <yoann.lopes@theqtcompany.com>

src/plugins/windowsaudio/qwindowsaudiodeviceinfo.cpp

@@ -453,7 +453,9 @@ QList<QByteArray> QWindowsAudioDeviceInfo::availableDevices(QAudio::Mode mode)
                 pPropBag->Release();
                 pMoniker->Release();
             }
+            pEnum->Release();
         }
+        pDevEnum->Release();
     }
     CoUninitialize();
 #else // Q_OS_WINCE