src: deprecate smalloc public functions

Upcoming V8 changes will make it impossible to keep supporting the
smalloc functionality so deprecate the functions in smalloc.h now
and tell people to switch to typed arrays.

This commit shuffles code around in smalloc.cc to avoid generating
the deprecation warnings when building io.js itself.

PR-URL: https://github.com/iojs/io.js/pull/1565


Reviewed-By: Trevor Norris <trev.norris@gmail.com>