[PATCH] math: Fix float conversion regressions with gcc-12 [BZ #28713]

[Paul Zimmermann]

       Dear Szabolcs,

> > While looking at that patch, in math/math.h, I thought new constants should
> > be declared as hexadecimal values?
> > 
> > +# define M_Ef		2.7182818284590452354f	/* e */
> > 
> > Otherwise this patch seems good to me.
> 
> this is a public header, i think decimal consts
> are used because hexadecimal is >=c99 only and
> not c++ compatible (at least before c++17).

ok, this looks good to me, all test still pass with gcc 12 (on x86_64 linux),
except elf/tst-env-setuid, but I believe this is unrelated.

Reviewed-by: Paul Zimmermann <Paul.Zimmermann@inria.fr>

Thanks!
Paul