Let scdaemon exit when no reader is available

[NIIBE Yutaka]

On 2012-12-04 at 10:50 +0100, Werner Koch wrote:
> Pushed.  Please feel free to push such changes yourself.

Thank you.  I will, in future.

Same treatment is also needed in 2.0 branch.  I am currently using
2.1.x with the change.  When I won't see any problem, say, for a week
or two, I will apply similar modification to 2.0 branch.

			*	*	*

I think that all my modifications are in master branch now, and all
problems I reported are solved somehow.

Next will be supporting some card reader with keypad which doesn't
have variable length input capability.
--