IO::Dir destructor

The IO::Dir destructor can clobber $! and other status variables.
This is a bad thing to do implicitly upon exiting a block.  Attached patch
fixes it.

-zefram

• IO::Dir destructor by Zefram
• Re: IO::Dir destructor by Rafael Garcia-Suarez
• AW: IO::Dir destructor by Dintelmann, Peter
• Re: AW: IO::Dir destructor by Bram
• Re: AW: IO::Dir destructor by Zefram
• Re: IO::Dir destructor by Steve Peters