Don't log if resolv_gethostby{name,addr} return no error

To avoid log spam, log their return value if the value
is an error. The following logs won't be printed.

  GetHostByNameHandler::run: result: Success
  GetHostByAddrHandler::run: result: Success

Fix: 223115382
Test: adb shell ping dns.google, then check the log
Change-Id: I180936a2d66a47142726054f001281a7ecd56f00