Fix exp in non-default rounding modes (bug 3976)

[Joseph S. Myers]

On Tue, 28 Feb 2012, David Miller wrote:

> From: "Joseph S. Myers" <joseph@codesourcery.com>
> Date: Wed, 29 Feb 2012 01:51:31 +0000 (UTC)
> 
> > No, it's not undefined;
> 
> I'm just saying that this is the exact language I've seen in Sun's
> documentation for libm, it's "undefined".

I think C99 and C11 Annex F are what's relevant here, not Sun's libm 
documentation.  The entire standard C library may be called in any 
rounding mode and must still meet the semantics given for each function.

-- 
Joseph S. Myers
joseph@codesourcery.com