RFR: 8364141: Remove LockingMode related code from x86

[Fredrik Bredberg]

Since the integration of [JDK-8359437](https://bugs.openjdk.org/browse/JDK-8359437) the `LockingMode` flag can no longer be set by the user, instead it's declared as `const int LockingMode = LM_LIGHTWEIGHT;`. This means that we can now safely remove all `LockingMode` related code from all platforms.

This PR removes `LockingMode` related code from the **x86** platform.

When all the `LockingMode` code has been removed from all platforms, we can go on and remove it from shared (non-platform specific) files as well. And finally remove the `LockingMode` variable itself.

Passes tier1-tier5 with no added problems.

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Commit messages:
 - 8364141: Remove LockingMode related code from x86

Changes: https://git.openjdk.org/jdk/pull/26552/files
  Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=26552&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8364141
  Stats: 637 lines in 10 files changed: 44 ins; 537 del; 56 mod
  Patch: https://git.openjdk.org/jdk/pull/26552.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/26552/head:pull/26552

PR: https://git.openjdk.org/jdk/pull/26552