Improve clog, clog10 handling of values with real or imaginary part slightly above 1 (bug 13629)

[Joseph S. Myers]

On Sat, 4 Aug 2012, Allan McRae wrote:

> I have not formally checked, but I assume this patch is the reason I
> started getting these errors on i686:

As log1pl uses x87 logarithm instructions, it's quite plausible that the 
exact results may vary between x86 implementations and so require more 
than one person to update ulps.

-- 
Joseph S. Myers
joseph@codesourcery.com