Gateway code was passing a char string as the package name to
`credssp_auth_init`. When using Unicode builds this fails since
`QuerySecurityPackageInfo` expects a wchar string.
Additionally with unicode builds, `credssp_auth_pkg_name` causes string
type mismatches in the gateway code where a char string is expected.
* Ensure negoToken is cleaned up in nla_free
* Renamed function credssp_auth_take_input_buffer now invalidates
input buffer an takes ownership of that buffer
