Fix compilation: Restore mistakenly removed constant definitions.

Originally committed as revision 17240 to svn://svn.ffmpeg.org/ffmpeg/trunk

libavcodec/xvmc.h

@@ -29,6 +29,12 @@
 #include <X11/extensions/XvMClib.h>
 
 
+//the surface should be shown, the video driver manipulates this
+#define MP_XVMC_STATE_DISPLAY_PENDING 1
+//the surface is needed for prediction, the codec manipulates this
+#define MP_XVMC_STATE_PREDICTION 2
+//this surface is needed for subpicture rendering
+#define MP_XVMC_STATE_OSD_SOURCE 4
 //                     1337    IDCT MCo
 #define MP_XVMC_RENDER_MAGIC 0x1DC711C0