Fixed build errors on systems without the DPMS extension

--HG--
extra : convert_revision : svn%3Ac70aab31-4412-0410-b14c-859654838e24/trunk%401750

src/video/x11/SDL_x11video.h

@@ -157,9 +157,7 @@ struct SDL_PrivateVideoData {
 
     /* Screensaver settings */
     int screensaver_timeout;
-#if SDL_VIDEO_DRIVER_X11_DPMS
     BOOL dpms_enabled;
-#endif
 };
 
 /* Old variable names */