s3-gse: Use the session key type, not the lucid context to set NEW_SPNEGO

s3-gse: Use the session key type, not the lucid context to set NEW_SPNEGO

Using gss_krb5_export_lucid_sec_context() is a problem with MIT krb5, as
it (reasonably, I suppose) invalidates the gssapi context on which it
is called.  Instead, we look to the type of session key which is
negotiated, and see if it not AES (or newer).

If we negotiated AES or newer, then we set GENSEC_FEATURE_NEW_SPENGO
so that we know to generate valid mechListMic values in SPNEGO.

Andrew Bartlett

Signed-off-by: Stefan Metzmacher <metze@samba.org>