urldata: make service names unconditional

The ifdefs have become quite long. Also, the condition for the
definition of CURLOPT_SERVICE_NAME and for setting it from
CURLOPT_SERVICE_NAME have diverged. We will soon also need the two
options for NTLM, at least when using SSPI, for
https://github.com/curl/curl/pull/1660.
Just make the definitions unconditional to make that easier.

Closes https://github.com/curl/curl/pull/2479