RFR: 8280823: Remove NULL check in DumpTimeClassInfo::is_excluded

[Ioi Lam]

On Fri, 28 Jan 2022 01:43:13 GMT, Yumin Qi <minqi at openjdk.org> wrote:

>> Please review this trivial change. The NULL check is not needed anymore because the ``DumpTimeClassInfo::_klass` field is never set to NULL.
>> 
>> Passed Oracle IT tiers 1~4
>
> Marked as reviewed by minqi (Reviewer).

Thanks @yminqi and @calvinccheung for the review

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PR: https://git.openjdk.java.net/jdk/pull/7249