Code cleanup: remove unused grease pencil pointer

source/blender/editors/space_view3d/space_view3d.c

@@ -706,7 +706,6 @@ static void *view3d_main_area_duplicate(void *poin)
 		new->gpuoffscreen = NULL;
 		new->ri = NULL;
 		new->render_engine = NULL;
-		new->gpd = NULL;
 		new->sms = NULL;
 		new->smooth_timer = NULL;
 		

source/blender/makesdna/DNA_view3d_types.h

@@ -101,8 +101,6 @@ typedef struct RegionView3D {
 	float clip_local[6][4]; /* clip in object space, means we can test for clipping in editmode without first going into worldspace */
 	struct BoundBox *clipbb;
 
-	struct bGPdata *gpd;		/* Grease-Pencil Data (annotation layers) */
-
 	struct RegionView3D *localvd; /* allocated backup of its self while in localview */
 	struct RenderInfo *ri;
 	struct RenderEngine *render_engine;