live, net-eth: add DHCP_TIMEOUT when appropriate

It's hardwired at 1/10 of the default /etc/net value
since 3 seconds are enough for properly functioning
DHCP servers in properly maintained networks (those
improper ones tend to have problems with 30 seconds
anyways), and waiting for too long makes users feel
bad for a reason.

Thanks msp@ for bringing attention to this.

features.in/live/live/image-scripts.d/50-setup-network

@@ -57,6 +57,7 @@ else
 		mkdir -p "$prefix"/eth0 && {
 		echo TYPE=eth
 		echo BOOTPROTO=dhcp
+		echo DHCP_TIMEOUT=3
 		} > "$prefix"/eth0/options
 	else
 		verbose "NOT configuring eth0 for DHCP"

features.in/net-eth/rootfs/image-scripts.d/50-net-eth

@@ -19,8 +19,10 @@ IFACEDIR="/etc/net/ifaces"
 write_iface() {
 	dir="$IFACEDIR/$iface"
 	mkdir -p "$dir"
+	append=
 	case "$proto" in
 	dhcp)
+		append="DHCP_TIMEOUT=3"
 		;;
 	static)
 		[ -n "$ipv4addr" ] || fatal "ipv4addr missing"
@@ -39,6 +41,7 @@ write_iface() {
 		echo "NM_CONTROLLED=$NMCTL"
 		echo "DISABLED=$NMCTL"
 		echo "#USE_IFPLUGD=yes"
+		[ -z "$append"] || echo "$append"
 	} > "$dir/options"
 }