[jdk11u] RFR: 8229258: Backport patch from JDK 14 to allow building with Clang 13

[VVD]

On Sun, 19 Dec 2021 02:55:01 GMT, Campbell Jones <duke at openjdk.java.net> wrote:

> This patch backports changes from JDK14 commit ae5615c6142a4dc0d9033462f4880d7b3c127e26. It does not rename the class to markWord as the original patch does, but instead converts markOop to a markWord equivalent in-place. This patch allows the JDK to be built with Clang 13, as it avoids undefined behavior. 
> 
> See the following for more information:
> - https://bugs.openjdk.java.net/browse/JDK-8229258
> - https://bugs.gentoo.org/817995
> - https://mail.openjdk.java.net/pipermail/hotspot-dev/2019-July/038704.html
> - https://mail.openjdk.java.net/pipermail/hotspot-dev/2019-July/038712.html
> - https://reviews.llvm.org/D99790#2678384

Commited? What version 11.x have it?

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PR: https://git.openjdk.org/jdk11u/pull/23