RFR: Merge jdk17 [v2]

[Jesper Wilhelmsson]

> Forwardport JDK 17 -> JDK 18

Jesper Wilhelmsson has updated the pull request with a new target base due to a merge or a rebase. The pull request now contains 103 commits:

 - Merge
 - 8269409: Post JEP 411 refactoring: core-libs with maximum covering > 10K
   
   Reviewed-by: lancea, naoto
 - 8269433: Remove effectively unused ReferenceProcessor::_enqueuing_is_done
   
   Reviewed-by: kbarrett, tschatzl
 - 8268902: Testing for threadObj != NULL is unnecessary in suspend handshake
   
   Reviewed-by: pchilanomate, dcubed
 - 8269222: Incorrect number of workers reported for reference processing
   
   Reviewed-by: tschatzl, sangheki
 - 8269122: The use of "extern const" for Register definitions generates poor code
   
   Reviewed-by: adinn, kbarrett, kvn
 - 8269003: Update the java manpage for JDK 18
   
   Reviewed-by: minqi
 - Merge
 - 8269261: The PlaceHolder code uses Thread everywhere but is always dealing with JavaThreads
   
   Reviewed-by: ccheung, coleenp
 - 8269129: Multiple tier1 tests in hotspot/jtreg/compiler are failing for client VMs
   
   Reviewed-by: kvn, iveresov
 - ... and 93 more: https://git.openjdk.java.net/jdk/compare/56240690...8863e7a7

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Changes: https://git.openjdk.java.net/jdk/pull/4619/files
 Webrev: https://webrevs.openjdk.java.net/?repo=jdk&pr=4619&range=01
  Stats: 27175 lines in 592 files changed: 16042 ins; 9481 del; 1652 mod
  Patch: https://git.openjdk.java.net/jdk/pull/4619.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk pull/4619/head:pull/4619

PR: https://git.openjdk.java.net/jdk/pull/4619