Clean up the provider status logic.

Clean up the provider status logic.

Provider status (done, running, not run) is now attached to the
provider-specific data of the client. A reference count of auth
instances is kept in the auth_client struct to determine if a client is
done or not.

This also moves a lot of the logic for manipulating provider data into
into the provider.h header for inlining (no point in a function call for
these simple accessors).