errno.h needs to be protected against multiple inclusion.

[J. Johnston]

Christopher Faylor wrote:
> 
> Hello,
> errno.h now has a typedef which needs to be protected against multiple
> inclusion.
> 
> I'd offer a patch but I'm wondering if there is a newlib standard way
> of doing this?  I also wonder if there should be a copyright notice in
> this file?
> 
> cgf

I caught this in my build testing this morning.  A fix has been applied.

-- Jeff J.