Allow ICMP for busybox traceroute

this will make the busybox-applet honor the "-I" option to use ICMP.
w/o this option UPD will be always used, see https://dev.openwrt.org/ticket/9212

Ported to LEDE by Committer

configs/common.config

@@ -15,6 +15,7 @@ CONFIG_BUSYBOX_CONFIG_MKSWAP=n
 CONFIG_BUSYBOX_CONFIG_SWAPONOFF=n
 CONFIG_BUSYBOX_CONFIG_TELNET=y
 CONFIG_BUSYBOX_CONFIG_FEATURE_TELNET_TTYPE=y
+CONFIG_BUSYBOX_CONFIG_FEATURE_TRACEROUTE_USE_ICMP=y
 CONFIG_OPENVPN_polarssl_ENABLE_LZO=y
 CONFIG_OPENVPN_polarssl_ENABLE_SMALL=y
 CONFIG_PACKAGE_6in4=m