libm: Fix log-related symbol aliases.

- Do the weak alias dance for log, log2, log10, log1p, and their
f/l variants.

(Not strictly necessary for log2 and log10 since nothing in the
math library itself uses them -- only a computer scientist would
use log2 and only an engineer would use log10 -- but let's just do
it the same for all our forestry.)

- Provide long double aliases on vax.

- Sprinkle RCS ids.

add missing symbols for non long double architectures.

Enable asinl, acosl, logl, coshl, tanhl, atanhl, asinhl and acoshl

* Fix pkgsrc/math/py-numpy and pkgsrc/graphics/py-matplotlib, for example.

move inclusion of <machine/ieee.h> to the ieee source files instead of
including it in math_private.h which is also used by the vax which is not ieee.

Bring in more long double functions from FreeBSD.

add missing symbols for non long double architectures.

Enable asinl, acosl, logl, coshl, tanhl, atanhl, asinhl and acoshl

* Fix pkgsrc/math/py-numpy and pkgsrc/graphics/py-matplotlib, for example.

move inclusion of <machine/ieee.h> to the ieee source files instead of
including it in math_private.h which is also used by the vax which is not ieee.

Bring in more long double functions from FreeBSD.