Defaulting to -fno-math-errno (was: Fwd: weird optimization in sin+cos, x86 backend)

[Gerald Pfeifer]

On Sun, 12 Feb 2012, Janne Blomqvist wrote:
> If one were to create a new libm, why not dispense with the errno
> stuff altogether, and make -fno-math-errno the default, at least in
> c99/c++11 modes (and set the math_errhandling macro properly). Some
> quick googling suggests that libm's which don't set errno are not that
> uncommon, e.g.

Yes, indeed.  Alas there does not seem to be an easy way to make
-fno-math-errno the default for a target?

(Otherwise I'd make this change for *-*-freebsd, for example.)

Gerald