TNC: Added preliminary TNC implementation for hostapd

TNC: Added preliminary TNC implementation for hostapd

This adds EAP-TNC method and TNCS (IF-IMV and IF-TNCCS) functionality.
There is no integration with EAP-TTLS and EAP-FAST at this point, so this
version is not yet suitable for real use (i.e., EAP-TNC can only be tested
outside a tunnel which is not an allowed configuration for deployment).
However, the basic TNCS functionality is more or less complete and this
version seems to interoperate with wpa_supplicant.