Unify DNS error codes reporting to the metrics

gethostbyname and getaddrinfo have their own error codes. Unify
these error codes to be POSIX EAI_*. This change is for better
and even more detailed DNS metrics, and will not impact on
applications.

Also clean up no-op code:
  - res_put_state

Bug: 113916551
Test: system/netd/tests/runtests.sh passed
Change-Id: Id4bbabc8d4dd5f2fdc8fabd38dab753cbb07d691