#2 Re-add identity to already running agent

[Robert Cernansky]

It would be usefull if pam_ssh will try to add identity if it finds already running agent for a user. This would handle situations like hibernation when identities are removed from agent and user is still logged in. The scenario would be following:

1. User logs in.
2. ssh-agent is started. Identity is unlocked and added to the agent.
3. User suspends the system to disk. Suspend script deletes all identities from ssh_agent for security reasons.
4. User resumes and unlocks the screen(saver) with its password.
5. pam_ssh founds that ssh-agent for that user is already running so it tries to unlock and add the identity to that running agent.