Fix BZ 18820 -- fmemopen may leak memory on failure

[Ondřej Bílka]

On Wed, Aug 12, 2015 at 10:00:31PM -0700, Paul Pluzhnikov wrote:
> Greetings,
> 
> I split out the "fix leak" part of BZ #18757 fix from
> https://sourceware.org/ml/libc-alpha/2015-08/msg00315.html
> 
> Tested on Linux/x86_64, no new failures.
> 
> Thanks,
>
Patch itself is ok but I found other bug that we don't set error values
there that should also be fixed.