[PATCH] Cleanup in istream.tcc

[Benjamin Kosnik]

>I suspect that it was not even considered when exceptions
>were added to iostreams. I would like to see this specified
>more precisely.

Martin, I'm working on this, and hope to have something to present
(informally, since I missed the pre-meeting deadline for this bit) in
Hawaii. Interested? There are too many exception-handling
inconsistencies in the io specification to ignore anymore...

-benjamin