[COMMITTED] Use C99 math macros

[Wilco Dijkstra]

> Joseph Myers wrote:
> On Wed, 3 Jun 2015, Wilco Dijkstra wrote:
> 
> > diff --git a/sysdeps/ieee754/ldbl-opt/nldbl-finite.c b/sysdeps/ieee754/ldbl-opt/nldbl-
> finite.c
> 
> > -  return __finite (x);
> > +  return finite (x);
> 
> Are you sure about this change?  "finite", as opposed to isfinite, is a
> non-type-generic BSD function; I'd expect this to cause the "finite"
> function name to be used for the call instead of __finite.  (Using
> isfinite here should be fine.)

Good catch - that's a typo, I meant isfinite indeed. There are a few other calls 
to finite so I don't think it causes namespace issues:

sysdeps/ieee754/ldbl-128ibm/s_fmal.c:       if ((finite ((double)x) && finite ((double)y)) && isinf
((double)z))
sysdeps/ieee754/ldbl-96/s_fma.c:      if (finite (x) && finite (y))

I'll fix these as well so they will become inlineable.

[ I guess this file is dead: sysdeps/ieee754/support.c:        if(!finite(x)) return(x); ]

Wilco