Now that we are building with C++11 features enabled, replace use
of NULL with nullptr.
The benefit of using nullptr is that it can never be confused for
an integral type because it does not support implicit conversions
to integral types except boolean - unlike NULL, which is defined
as a literal `0`.
Because of behavior change of some V8 APIs (they mostly became more
strict), following modules needed to be fixed:
* crypto: duplicate prototype methods are not allowed anymore
* contextify: some TryCatch trickery, the binding was using it
incorrectly
* util: maximum call stack error is now crashing in a different place
Reviewed-By: Trevor Norris <trevnorris@gmail.com>
PR-URL: https://github.com/joyent/node/pull/8476