[PATCH] Use builtins in fabs implementations

[Joseph Myers]

On Fri, 22 May 2015, Wilco Dijkstra wrote:

> Since GLIBC is built with a modern GCC which always inlines 
> __builtin_fabs, it is safe to use the builtin for the definitions of 
> fabs and fabsf (fabsl is typically emulated and unsafe in some cases, 
> see https://sourceware.org/ml/libc-alpha/2015-05/msg00336.html). This 
> means targets no longer need to define their own implementations.
> 
> OK for commit?

OK if you've at least run the math/ tests with clean results for at least 
one configuration.

-- 
Joseph S. Myers
joseph@codesourcery.com