#128 use_sso undefined warning

[zwerver]

Version v8.1.13 - r527 generates a warning about an unknown variable in all pages:

Notice: Undefined variable: use_sso in E:\sites\zw3rv3r.local\public_html\addressbook\include\login.inc.php on line 91

This may be generated when dbconnect.php (where the variable is declared) is included after login.inc.php is included.