RFR: 8357481: Excessive CompileTask wait/notify monitor creation

[Aleksey Shipilev]

See bug for rationale.

This PR implements the 2nd solution from the bug: lift the lock to be global. As described in the bug, excess locking work would realistically affect Xcomp, and only in a minor way. But we will reap a minor footprint/latency benefit by not constructing the lock for every `CompileTask`.

Additional testing:
 - [x] Linux x86_64 server fastdebug, `compiler`
 - [ ] Linux x86_64 server fastdebug, `all`
 - [ ] Linux AArch64 server fastdebug, `all`

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Commit messages:
 - Fix

Changes: https://git.openjdk.org/jdk/pull/25364/files
  Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=25364&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8357481
  Stats: 26 lines in 5 files changed: 5 ins; 10 del; 11 mod
  Patch: https://git.openjdk.org/jdk/pull/25364.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/25364/head:pull/25364

PR: https://git.openjdk.org/jdk/pull/25364