[master] RFR: OMWorld: Cleanup BasicLock header [v2]

[Axel Boldt-Christmas]

> 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.

Axel Boldt-Christmas has updated the pull request with a new target base due to a merge or a rebase. The incremental webrev excludes the unrelated changes brought in by the merge/rebase. The pull request contains three additional commits since the last revision:

 - Merge remote-tracking branch 'upstream_lilliput/master' into lilliput-om-cleanup-basiclock-header
 - Fix condition
 - BasicLock Restructure (includes JVMCI and zero changes)

-------------

Changes:
  - all: https://git.openjdk.org/lilliput/pull/162/files
  - new: https://git.openjdk.org/lilliput/pull/162/files/b54babc1..ca28a78a

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=lilliput&pr=162&range=01
 - incr: https://webrevs.openjdk.org/?repo=lilliput&pr=162&range=00-01

  Stats: 76 lines in 5 files changed: 52 ins; 18 del; 6 mod
  Patch: https://git.openjdk.org/lilliput/pull/162.diff
  Fetch: git fetch https://git.openjdk.org/lilliput.git pull/162/head:pull/162

PR: https://git.openjdk.org/lilliput/pull/162