Use NLMSG_TAIL

(Logical change 1.127)
diff --git a/tc/q_tbf.c b/tc/q_tbf.c
index 8f8c277..d251435 100644
--- a/tc/q_tbf.c
+++ b/tc/q_tbf.c
@@ -187,13 +187,13 @@
 		opt.peakrate.mpu = mpu;
 	}
 
-	tail = (struct rtattr*)(((void*)n)+NLMSG_ALIGN(n->nlmsg_len));
+	tail = NLMSG_TAIL(n);
 	addattr_l(n, 1024, TCA_OPTIONS, NULL, 0);
 	addattr_l(n, 2024, TCA_TBF_PARMS, &opt, sizeof(opt));
 	addattr_l(n, 3024, TCA_TBF_RTAB, rtab, 1024);
 	if (opt.peakrate.rate)
 		addattr_l(n, 4096, TCA_TBF_PTAB, ptab, 1024);
-	tail->rta_len = (((void*)n)+NLMSG_ALIGN(n->nlmsg_len)) - (void*)tail;
+	tail->rta_len = (void *) NLMSG_TAIL(n) - (void *) tail;
 	return 0;
 }