Fix (unreported) crash when drawing armatures' poses in some cases.

Was affecting armatures' pose drawing code, could try to draw with
non-updated pose, which may contain NULL bone pointers (e.g. after some
data-block management tool execution, like make local, remapping, etc.).

source/blender/editors/space_view3d/drawarmature.c

@@ -2723,6 +2723,11 @@ bool draw_armature(Scene *scene, View3D *v3d, ARegion *ar, Base *base,
 	else {
 		/*	Draw Pose */
 		if (ob->pose && ob->pose->chanbase.first) {
+			/* We can't safely draw non-updated pose, might contain NULL bone pointers... */
+			if (ob->pose->flag & POSE_RECALC) {
+				BKE_pose_rebuild(ob, arm);
+			}
+
 			/* drawing posemode selection indices or colors only in these cases */
 			if (!(base->flag & OB_FROMDUPLI)) {
 				if (G.f & G_PICKSEL) {