lib: deprecate the smalloc module

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

The module is used in core in a few places so this commit makes the
public module private and replaces the public part with wrappers that
print deprecation notices.

PR-URL: https://github.com/iojs/io.js/pull/1564


Reviewed-By: Domenic Denicola <domenic@domenicdenicola.com>
Reviewed-By: Trevor Norris <trev.norris@gmail.com>