androiddump uses nonblocking connect on Windows, trying 10 times
with 1ms timeouts in select(). (This is short, but it's generally
trying to connect to the loopback interface.) On UN*X, it uses blocking
sockets, also trying 10 times, with SO_SNDTIMEO set to 2s.
Generally the socket returns nears instaneously, because it's
trying to connect to localhost. If the loopback interface goes
down, however, this results in 20s of timeouts.
Use nonblocking sockets on UN*X as well.
Related to #13104, #15295
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