uxa/video: only call intel_xvmc_adaptor_init when xvmc is enabled

Build regression from

commit 616dea2c67
Author: Keith Packard <keithp@keithp.com>
Date:   Thu Jul 24 10:27:55 2014 -0700

    Rename uxa-specific functions and structs

Signed-off-by: Tobias Jakobi <tjakobi@math.uni-bielefeld.de>

src/uxa/intel_video.c

@@ -239,8 +239,10 @@ void intel_video_init(ScreenPtr screen)
 		intel->XvEnabled = FALSE;
 	}
 
+#ifdef INTEL_XVMC
         if (texturedAdaptor)
                 intel_xvmc_adaptor_init(screen);
+#endif
 
 	free(adaptors);
 }