SDL_windowsmodes: fix WIN_GetDisplayNameVista source identifier number

This was getting the wrong monitor's name because the source identifier
was not being included in the DisplayConfigGetDeviceInfo request.

src/video/windows/SDL_windowsmodes.c

@@ -256,6 +256,7 @@ WIN_GetDisplayNameVista(const WCHAR *deviceName)
             sourceName.header.adapterId = paths[i].targetInfo.adapterId;
             sourceName.header.type = DISPLAYCONFIG_DEVICE_INFO_GET_SOURCE_NAME;
             sourceName.header.size = sizeof (sourceName);
+            sourceName.header.id = paths[i].sourceInfo.id;
             rc = pDisplayConfigGetDeviceInfo(&sourceName.header);
             if (rc != ERROR_SUCCESS) {
                 break;