g3dvl: Basic subpicture support.

RGB subpictures only at the moment.
diff --git a/src/gallium/state_trackers/xorg/xvmc/xvmc_private.h b/src/gallium/state_trackers/xorg/xvmc/xvmc_private.h
index 5fb994d..6e1b863 100644
--- a/src/gallium/state_trackers/xorg/xvmc/xvmc_private.h
+++ b/src/gallium/state_trackers/xorg/xvmc/xvmc_private.h
@@ -55,4 +55,12 @@
 	XvMCContext *context;
 } XvMCSurfacePrivate;
 
+typedef struct
+{
+	struct pipe_surface *sfc;
+	/* Some XvMC functions take a subpicture but not a context,
+	   so we keep track of which context each subpicture belongs to. */
+	XvMCContext *context;
+} XvMCSubPicturePrivate;
+
 #endif /* xvmc_private_h */