Fix Get_Error() usage, take II

Fix Get_Error() usage, take II

This should fix the following compiler warning:

  resolve.c:113:1: warning: ‘Get_Error’ defined but not used
    [-Wunused-function]

Which can happen, because the logic of commit 543f44bf isn't sufficient:
Get_Error() is only used when neither HAVE_WORKING_GETADDRINFO nor
HAVE_GETNAMEINFO are set ...

Enhances 543f44bf.
Closes #241.