[patch,target] Fix ppc-darwin issue with long double intrinsics (PR25477)

[Joseph S. Myers]

On Sat, 23 Feb 2008, FX Coudert wrote:

> > +      /*darwin_patch_builtin (BUILT_IN_NANL);*/ /* Broken for now since it
> > +        is defined as DEF_GCC_BUILTIN when it is also a C99 function.  */

Note that this (builtin nan*) is bug 19984, which explains the history 
behind the use of DEF_GCC_BUILTIN.

-- 
Joseph S. Myers
joseph@codesourcery.com