RFR: 8289520: G1: Remove duplicate checks in G1BarrierSetC1::post_barrier

[Thomas Schatzl]

On Thu, 30 Jun 2022 12:08:59 GMT, Albert Mingkun Yang <ayang at openjdk.org> wrote:

> Simple change of removing effectively dead code.
> 
> Test: tier1-3

Lgtm.

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Marked as reviewed by tschatzl (Reviewer).

PR: https://git.openjdk.org/jdk/pull/9333