RFR: JDK-8303047: avoid NULL after 8301661

[David Holmes]

On Wed, 22 Feb 2023 08:46:51 GMT, Matthias Baesken <mbaesken at openjdk.org> wrote:

> JDK-8301661 introduced a few usages of NULL in os_bsd.cpp and os_windows.cpp. This should be avoided and replaced by nullptr .

Good and trivial. Thanks for fixing.

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Marked as reviewed by dholmes (Reviewer).

PR: https://git.openjdk.org/jdk/pull/12709