Emit pending deprecation warnings.
Pending deprecations are generally identical to a runtime deprecation with the
notable exception that they are turned off by default and will not be emitted
unless either the --pending-deprecation
command-line flag, or the
NODE_PENDING_DEPRECATION=1
environment variable, is set. Pending deprecations
are used to provide a kind of selective “early warning” mechanism that
developers may leverage to detect deprecated API usage.