[v3] Fix libstdc++/50880

[Paolo Carlini]

Hi,

> On Thu, Oct 27, 2011 at 6:02 AM, Paolo Carlini <paolo.carlini@oracle.com> wrote:
>> Hi,
>> 
>> tested x86_64-linux (with _GLIBCXX_USE_C99_COMPLEX_TR1 manually set to zero
>> for the affected function), committed to mainline. Will go in 4.6.3 too.
> 
> Hmm, why is the test of the form x < 0.0, and not testing the sign of x?

I don't know, personally I don't care much about this fallback code. If you want I can do the change.

Paolo