Draw grease pencil after masks

Looks like drawing grease pencil before masks was affecting projection matrix
somehow which made masks invisible

Anyway, drawing GP actually shall happen after masks to match how it works
in other areas.

source/blender/editors/space_clip/space_clip.c

@@ -1101,9 +1101,6 @@ static void clip_main_area_draw(const bContext *C, ARegion *ar)
 
 	clip_draw_main(sc, ar, scene);
 
-	/* Grease Pencil */
-	clip_draw_grease_pencil((bContext *)C, 1);
-
 	if (sc->mode == SC_MODE_MASKEDIT) {
 		int x, y;
 		int width, height;
@@ -1147,6 +1144,9 @@ static void clip_main_area_draw(const bContext *C, ARegion *ar)
 		glPopMatrix();
 	}
 
+	/* Grease Pencil */
+	clip_draw_grease_pencil((bContext *)C, 1);
+
 	/* reset view matrix */
 	UI_view2d_view_restore(C);