[net_util] fix reporting getaddrinfo() error
[net_util] fix reporting getaddrinfo() error

An example of error output:
  on Linux, prior to this fix:

    Network error: Unable to lookup FQDN: Success (error 0)

  on Linux, after this fix:

    Network error: unable to look up canonical hostname for \
      localhost 'mega.turbo': Name or service not known

Change-Id: I2d5ba87b9ea050724367610461bae22c9471a103
Reviewed-on: http://gerrit.cloudera.org:8080/7368
Tested-by: Alexey Serbin <864f6b82bd94e8dda64141d4274519ee66e0102e@cloudera.com>
Reviewed-by: Dan Burkert <4ef91e292a55314d2653d35ff669a6bd939ce515@apache.org>

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