RFR: 8272165: Consolidate mark_must_be_preserved() variants

[Thomas Schatzl]

On Mon, 9 Aug 2021 18:25:35 GMT, Roman Kennke <rkennke at openjdk.org> wrote:

> We have markWord::mark_must_be_preserved() and markWord::mark_must_be_preserved_for_promotion_failure(). We used to have slightly different implementations when we had BiasedLocking, but now they are identical and used for identical purposes too. Let's remove what we don't need.
> 
> Testing:
>  - [ ] hotspot_gc
>  - [ ] tier1
>  - [ ] tier2

Lgtm and trivial removal.

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Marked as reviewed by tschatzl (Reviewer).

PR: https://git.openjdk.java.net/jdk/pull/5057