ntlm: We prefer 'CURLcode result'

Continuing commit 0eb3d15ccb more return code variable name changes.
ntlm: Renamed SSPI based input token variables

Code cleanup to try and synchronise code between the different SSPI
based authentication mechanisms.
ntlm: Renamed handle variables to match other SSPI structures

Code cleanup to try and synchronise code between the different SSPI
based authentication mechanisms.
ntlm: Changed handles to be dynamic like other SSPI handles

Code cleanup to try and synchronise code between the different SSPI
based authentication mechanisms.