libbb: add strncpy_IFNAMSIZ

function                                             old     new   delta
...
udhcp_read_interface                                 225     220      -5
brctl_main                                          1151    1146      -5
add_interface                                        109     104      -5
ipaddr_list_or_flush                                2174    2167      -7
do_add_ioctl                                          88      80      -8
vconfig_main                                         249     240      -9
do_del_ioctl                                          78      68     -10
do_iplink                                           1186    1173     -13
do_if_fetch                                          766     753     -13
buffer_fill_and_print                                196     179     -17
parse_args                                          1709    1684     -25
------------------------------------------------------------------------------
(add/remove: 0/0 grow/shrink: 2/20 up/down: 11/-140)         Total: -129 bytes


diff --git a/networking/traceroute.c b/networking/traceroute.c
index 29cebfa..5d1baac 100644
--- a/networking/traceroute.c
+++ b/networking/traceroute.c
@@ -447,7 +447,7 @@
 		 * SIOCGIFFLAGS stomps over it because the requests
 		 * are returned in a union.)
 		 */
-		strncpy(ifr.ifr_name, ifrp->ifr_name, sizeof(ifr.ifr_name));
+		strncpy_IFNAMSIZ(ifr.ifr_name, ifrp->ifr_name);
 		if (ioctl(fd, SIOCGIFFLAGS, (char *)&ifr) < 0) {
 			if (errno == ENXIO)
 				continue;