lgamma_r and lgammaf_r return the wrong sign for -0.f

[Steve Kargl]

On Fri, Sep 12, 2014 at 03:17:02PM -0700, enh via freebsd-numerics wrote:
> On Fri, Sep 12, 2014 at 3:05 PM, Steve Kargl
> >   F.9.5.3 The lgamma functions
> >   -- lgamma(1) returns +0.
> >   -- lgamma(2) returns +0.
> >   -- lgamma(x) returns +inf and raises the ``divide-by-zero'' floating-point
> >      exception for x a negative integer or zero.
> >   -- lgamma(-inf) returns +inf.
> >   -- lgamma(+inf) returns +inf.
> >
> > See the 3rd bullet.  -0 is 0 and -0 is a negative integer.

Of course, neither POSIX nor ISO C specify lgamma_r() only lgamma.
I just spent too much time on the 'divide-by-zero' bug, and 
conflated that with signgam.

> > POSIX appears to defer to ISO C.  n1570.pdf (committe draft for C11)
> > has (almost?) identical text.
> >
> >> patch below (whitespace mangled courtesy of gmail). i'd prefer to wait
> >> for this to be fixed in FreeBSD and pull down the fix rather than just
> >> fix it locally.
> >
> > I have a bigger patch coming with ld80 and ld128 version of lgammal
> > and lgammal_r.
> 
> sorry, i haven't even looked at the *l variants.

I only just finished writing the *l variants.  It took me 
a long time to unwind the comments in e_lgamma_r.c,
so that I could write the long double versions.

-- 
Steve