RFR: Merge jdk16

[Jesper Wilhelmsson]

Forwardport JDK 16 -> JDK 17

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Commit messages:
 - Merge
 - 8259025: Record compact constructor using Objects.requireNonNull
 - 8259276: C2: Empty expression stack when reexecuting tableswitch/lookupswitch instructions after deoptimization
 - 8260284: C2: assert(_base == Int) failed: Not an Int

The webrevs contain the adjustments done while merging with regards to each parent branch:
 - master: https://webrevs.openjdk.java.net/?repo=jdk&pr=2248&range=00.0
 - jdk16: https://webrevs.openjdk.java.net/?repo=jdk&pr=2248&range=00.1

Changes: https://git.openjdk.java.net/jdk/pull/2248/files
  Stats: 114 lines in 4 files changed: 107 ins; 3 del; 4 mod
  Patch: https://git.openjdk.java.net/jdk/pull/2248.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk pull/2248/head:pull/2248

PR: https://git.openjdk.java.net/jdk/pull/2248