init: Allow functions to fail if they are unsupported.
init: Allow functions to fail if they are unsupported.

PKCS#11 does not define what a "stub" unsupported function should do,
other then it should "simply" return CKR_FUNCTION_NOT_SUPPORTED.

Some implementations (chaps, softhsm2) do check state/arguments and return
example CKR_CRYPTOKI_NOT_INITIALIZED, CKR_SESSION_HANDLE_INVALID, e.t.c.
while others do not.

Yubico/pkcs11test,Yubico/pkcs11test,Yubico/pkcs11test,Yubico/pkcs11test