• fix CURLcode vs. LDAP result code confusion.
  Return LDAP_NO_MEMORY when Curl_create_sspi_identity() fails,
  since it can only return CURLE_OUT_OF_MEMORY as error.
• use ULONG for result code on Windows. Drop casts.
• use portable curl_ldap_num_t. Drop casts.
• replace magic number 0 with LDAP_SUCCESS.
• compare with LDAP_SUCCESS instead of assuming non-zero.
  (where necessary.)
• add/fix #endif comments.
• fix indentation.

w/o sp https://github.com/curl/curl/pull/18888/files?w=1