Destroying valid sessions

[commonism]

Trying to access a non existing object results in all sessions to the token getting closed.

https://github.com/OpenSC/libp11/blob/master/src/p11_slot.c#L331

PKCS11_release_all_slots
pkcs11_release_slot
CRYPTOKI_call(ctx, C_CloseAllSessions(priv->id));

Closing only the current session as proposed here commonism@86a9429 (part of #7) is proposed therefore.

[nmav]

The patch isn't really correct. C_CloseAllSessions() closes all sessions in the current slot (not token), which is the expected behavior. Your change doesn't really close anything because you input a slot ID instead of session ID. I'm closing this issue, but feel free to reopen if I have misunderstood it.