RFR: 8297864: Dead code elimination

[Robbin Ehn]

Please consider removing all this dead code.
I did not have any good way of splitting this up and I did not see any benefit is just splitting it up 'just because'.
There is one commit per file couple.
Not much else to say, passes t1-4 and I can build:
linux-aarch64-debug,linux-arm32-debug,linux-ppc64le-debug,linux-s390x-debug,linux-x86,linux-x86-debug,macosx-aarch64-debug,macosx-x64,macosx-x64-debug,windows-x64-debug,windows-x86-debug and zero-x64-debug
Some of them I also built release.

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Commit messages:
 - vframeArray
 - vframe
 - timerTrace
 - timer
 - threadStatisticalInfo
 - threadSMR
 - threads
 - threadHeapSampler
 - thread
 - synchronizer
 - ... and 42 more: https://git.openjdk.org/jdk/compare/79411478...4dd56f2a

Changes: https://git.openjdk.org/jdk/pull/11439/files
 Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=11439&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8297864
  Stats: 1058 lines in 100 files changed: 0 ins; 1037 del; 21 mod
  Patch: https://git.openjdk.org/jdk/pull/11439.diff
  Fetch: git fetch https://git.openjdk.org/jdk pull/11439/head:pull/11439

PR: https://git.openjdk.org/jdk/pull/11439