X neotest: Determine machine IP addresses via `ip ...` directly, not `getent ...`

The problem with `getent hosts ...` is that /etc/hosts has to be
manually prepared for it to work and it just does not scale and is error
prone.

So just extract machine global IP addresses at runtime as configured on
the interfaces.

go/neo/t/neotest

@@ -143,10 +143,24 @@ $@
 
 # init_net	- initialize networking
 init_net() {
-	# determine our external address IPv4 or IPv6
-	# FIXME better parse `ip addr` - getent relies on /etc/hosts which needs to be manually setup
-	myaddr=$(getent hosts `hostname` |grep -v 127.0 |awk '{print $1}')
-	test -n "$myaddr" || die "init_net: cannot determine my network address"
+	# determine our external addresses IPv4 or IPv6
+	# 2: wlan0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc mq state UP group default qlen 1000
+	#     inet 192.168.102.52/24 brd 192.168.102.255 scope global dynamic wlan0
+	#        valid_lft 82495sec preferred_lft 82495sec
+	#
+	# 1: lo: <LOOPBACK,UP,LOWER_UP> mtu 65536 state UNKNOWN qlen 1000
+	#     inet6 2401:5180:0:37::1/64 scope global
+	#        valid_lft forever preferred_lft forever
+	# 2: wlan0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 state UP qlen 1000
+	#     inet6 2401:5180:0:1d:429a:e612:c957:29/64 scope global noprefixroute dynamic
+	#        valid_lft 86232sec preferred_lft 14232sec
+	myaddr4v=(`ip -4 addr show scope global |grep inet |awk '{print $2}' |sed -e 's|/.*$||'`)
+	myaddr6v=(`ip -6 addr show scope global |grep inet |awk '{print $2}' |sed -e 's|/.*$||'`)
+	test "${#myaddr4v[@]}" -gt 0 || die "init_net: cannot determine my IPv4 network addresses"
+	test "${#myaddr6v[@]}" -gt 0 || die "init_net: cannot determine my IPv6 network addresses"
+
+	# prefer ipv4 for now
+	myaddr="${myaddr4v[0]}"
 
 	# port allocations ([] works for IPv4 too)
 	Abind=[$myaddr]:5551	# NEO admin
@@ -449,7 +463,12 @@ lspci1() {
 # show information about local system (os, hardware, versions, ...)
 system_info() {
 	echo -n "# "; date --rfc-2822
-	echo    "# `whoami`@`hostname --fqdn` ($myaddr)";
+	echo -n "# `whoami`@`hostname --fqdn` ("
+	echo -n "${myaddr6v[0]}"
+	test "${#myaddr6v[@]}" -eq 1 || echo -n " (+ $((${#myaddr6v[@]} - 1))·ipv6)"
+	echo -n " ${myaddr4v[0]}"
+	test "${#myaddr4v[@]}" -eq 1 || echo -n " (+ $((${#myaddr4v[@]} - 1))·ipv4)"
+	echo ")"
 	echo -n "# "; uname -a
 
 	# cpu