Prefer new libm function wrappers for !LIBM_SVID_COMPAT [committed]

[Joseph Myers]

On Fri, 29 Sep 2017, Szabolcs Nagy wrote:

> i think this change made the gammaf, gamma, gammal
> weak aliases disappear on new targets.

And it seems for static linking.

> (at least i don't have those symbols after i rebase
> the arm/ilp32 patches now, they used to come from
> math/w_lgamma*_compat2.os)
> 
> i don't think it's safe to remove them for new targets
> since they are still in the public math.h

I think that means new targets and static linking should get them from 
w_lgamma_template.c.  That is, there should be w_lgamma.c, w_lgammaf.c and 
w_lgammal.c that include the template in the usual way then (for 
!LIBM_SVID_COMPAT) create the additional aliases (since we don't want the 
old versions of wrappers used on new targets - and as gamma is a Unix98 
interface, it should stay around, but as it's obsolescent, we don't want 
it for any _FloatN / _FloatNx types).

-- 
Joseph S. Myers
joseph@codesourcery.com