[master] RFR: OMWorld: Cleanup BasicLock header

[Stefan Karlsson]

On Mon, 22 Apr 2024 13:50:04 GMT, Axel Boldt-Christmas <aboldtch at openjdk.org> wrote:

> Cleanup the usage of the header field in BasicLock. Because the asserts are stronger now I also cleanup the zero usage of the BasicLock. Because https://bugs.openjdk.org/browse/JDK-8307532 is not yet implemented I have not tested this interaction but as this now restricts the displaced header in the BasicLock to only LM_LEGACY something had to be done for LM_MONITOR support. 
> 
> This also changes symbols exposed through JVMCI so it may take extra effort to get this through. 
> 
> Similarly to #161 some changes could be upstreamed, and here there is already a distinction as neither `LM_LIGHTWEIGHT` nor `LM_MONITOR` uses the displaced header.

Marked as reviewed by stefank (Committer).

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PR Review: https://git.openjdk.org/lilliput/pull/162#pullrequestreview-2019819149