libiproute: make rt_addr_n2a() and format_host() return auto strings

function                                             old     new   delta
rt_addr_n2a                                           56      53      -3
print_addrinfo                                      1227    1178     -49
print_neigh                                          933     881     -52
print_rule                                           689     617     -72
print_tunnel                                         640     560     -80
print_route                                         1727    1588    -139
------------------------------------------------------------------------------
(add/remove: 0/0 grow/shrink: 0/6 up/down: 0/-395)           Total: -395 bytes

Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
diff --git a/networking/libiproute/ipneigh.c b/networking/libiproute/ipneigh.c
index 6588c12..179505c 100644
--- a/networking/libiproute/ipneigh.c
+++ b/networking/libiproute/ipneigh.c
@@ -91,7 +91,6 @@
 	struct ndmsg *r = NLMSG_DATA(n);
 	int len = n->nlmsg_len;
 	struct rtattr *tb[NDA_MAX+1];
-	char abuf[256];
 
 	if (n->nlmsg_type != RTM_NEWNEIGH && n->nlmsg_type != RTM_DELNEIGH) {
 		bb_error_msg_and_die("not RTM_NEWNEIGH: %08x %08x %08x",
@@ -155,8 +154,8 @@
 		printf("%s ",
 		       format_host(r->ndm_family,
 				   RTA_PAYLOAD(tb[NDA_DST]),
-				   RTA_DATA(tb[NDA_DST]),
-				   abuf, sizeof(abuf)));
+				   RTA_DATA(tb[NDA_DST]))
+		);
 	}
 	if (!G_filter.index && r->ndm_ifindex)
 		printf("dev %s ", ll_index_to_name(r->ndm_ifindex));