Issue #847: protocol deadlock in NLA

fix ber_get_content_length and der_get_content_length to work for values
around 0x80 and 0x100
Fix nego_token, auth_info and pub_key_auth content length calculation in
credssp_send to fix a lockup in NLA protocol.
Merge pull request #1011 from ago1024/master

Issue #847: protocol deadlock in NLA