cmake: fix NTLM detection when CURL_DISABLE_HTTP defined

Updated following changes in commit f0d860d.

Acked-by: Brad King <brad.king@kitware.com>
Signed-off-by: Peter Wu <peter@lekensteyn.nl>
cmake: add Kerberos to the supported features

Updated following commit eda919f and a4b7f71.

Acked-by: Brad King <brad.king@kitware.com>
Signed-off-by: Peter Wu <peter@lekensteyn.nl>