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.

neotest part pending.

compared to tgro5:

tgro0   py -> noise (ZEO, NEO/pylite, NEO/pysql, partly neo/go)
tgro10  py=no-noise, tpy~=tgro5; tgo serial~same, +prefetch more noise (?) 40|65
tgro15  lat_tcp 1B 49->45 sometime (consistently) otherwise more-or-less same
tgro20  lat_tcp 4K 170µs->167µs (c)
tgro25  lat_tcp 4K 170µs->167µs (c), lat_tcp 4K 175 -> 171µs (go)
        ZEOv a bit
        go-go + prefetch !sha1 -> noise + higher (~65µs -> 70 - 110µs)

txc40µs4f seems to be worse than txc200µs4f

Link and TCP* latencies are ~ same and stable.

Compared to b288e62f py timings stabilize:

ZEO		~580-1045μs	-> 585µs
NEO/pylite	~600-700μs	-> ~550-570µs	(Cpy)
NEO/pylite	~525-580μs	-> ~450µs	(Cgo)
NEO/pysql	~820-930μs	-> ~840µs	(Cpy)
NEO/pysql	~740-800μs	-> ~740µs	(Cgo)

Go timings get a bit worse:

NEO/go		~360µs		-> ~380µs	(Cpy)
NEO/go		~160µs		-> ~165-170µs	(Cgo)
NEO/go-nosha1	~140µs		-> ~150µs

Compared to 15a9ccef go+pretech128 timings stabilize:

go-go+prefetch128		~65-160µs	-> ~40-45µs, 60µs(x1)
go-go+prefetch128 (!sha1)	~60-150µs	-> ~60µs,    40µs(x1)

Compared to run from Oct10 txc settings were not changed and they are now
200μs/4f/0μs-irq/0f-irq on both machines instead of 200μs/4f/0μs-irq/0f-irq on
neo1 and 200μs/0f/0μs-irq/0f-irq on neo2.

The noise about py runs remains.

Go-go serial time remains the same ~155μs without much noise, but Go-go time
with +prefetch128 gets worse:

NEO/go Cgo +prefetch128

        ~45μs   -> 65 - 160μs

Probably it makes sense to tune txc too...

See previous commit for details about why latency is bad for TCP payload > MSS
without TSO.

Compared to latest neo1-neo2 timings from Oct05 (C-states disabled, no
rx-delay) it improves:

TCP1             ~45μs  ->   ~45μs
TCP1472         ~430μs			# TCP lat. anaomaly
TCP1400                 ->  ~120μs	# finally
TCP1500                 ->  ~130μs	# fixed
TCP4096         ~285μs  ->  ~170μs	# !

ZEO             ~670μs  ->  ~580-1045μs (?)
NEO/pylite      ~605μs  ->  ~600-700μs  (?)     (Cpy)
NEO/pylite      ~505μs  ->  ~525-580μs  (?)     (Cgo)
NEO/pysql       ~900μs  ->  ~820-930μs  (?)     (Cpy)
NEO/pysql       ~780μs  ->  ~740-800μs  (?)     (Cgo)
NEO/go          ~430μs  ->  ~360μs              (Cpy)	# <-- NOTE
NEO/go          ~210μs  ->  ~160μs              (Cgo)	# <-- NOTE
NEO/go-nosha1   ~190μs  ->  ~140μs			# <-- NOTE

not sure about noise in pure py runs but given raw tcp latency absolutely
improves this should be a good change to make.

On neo1 - neo2 without TSO latency becomes very poor in lat_tcp when
payload size becomes greater TCP MSS (lat_tcp -m 1448 ~ 130μs; lat_tcp
-m 1449 ~ 500μs and more)

e.g.

	neotest cpustat ls

Same a before with added information.
In particular z6001-z600 shows there is no TCP RR step-wise 400μs increase
while going 1400B -> 1500B as it is currently the case on RTL.

Same as before but with more information and adjusted ping and TCP RR.

In particular TCP RR shows:

TCPRR1400	~ 120μs
TCPRR1500	~ 430μs

The time when this increases step-wise is when TCP packet crosses fitting 1 ethernet frame.
It does not happen on z600* with their current settings.