Adding __float128 (i.e TS 18661-3)

[Paul E. Murphy]

On 06/09/2016 03:00 PM, Paul E. Murphy wrote:
> 
> Picking up here as a reasonable place to continue the
> discussion on ABI and API for float128 (or any future
> TS 18661-3 derived type).
> 
> 
> For any new TS 18661-3 derived type, I propose the
> following new functions and ABI be exposed through
> libm via math.h:
> 
> 	From TS 18661-3:
> 
> 	acosh acos asinh asin
> 	atan2 atanh atan cabs
> 	cacosh cacos carg casinh
> 	casin catanh catan cbrt
> 	ccosh ccos ceil cexp
> 	cimag clog conj copysign
> 	cosh cos cpow cproj
> 	creal csinh csin csqrt
> 	ctanh ctan erfc erf
> 	exp2 exp expm1 fabs
> 	fdim floor fma fmax
> 	fmin fmod frexp hypot
> 	ilogb ldexp lgamma llrint
> 	llround log10 log1p log2
> 	logb log lrint lround
> 	modf nanf nearbyint nextafter
> 	pow remainder remquo rint
> 	round scalbln scalbn 
> 	sinh sin sqrt tanh
> 	tan tgamma trunc nextup
> 	nextdown.
> 
> 	From GNU:
> 
> 	exp10 clog10 j0l j1l
> 	jnl lgamma?_r sincos
> 	y0 y1 yn
>

Err, anything taking a _Complex _FloatN argument should only
be declared via complex.h.

Likewise tgmath.h needs updated to correctly select
__float128 functions.