RFR: Merge jdk

[Mikael Vidstedt]

Merge in jdk-16+28

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Commit messages:
 - Merge jdk
 - 8257837: Performance regression in heap byte buffer views
 - 8258005: JDK build fails with incorrect fixpath script
 - 8257602: Introduce JFR Event Throttling and new jdk.ObjectAllocationSample event (enabled by default)
 - 8257483: C2: Split immediate vector rotate from RotateLeftV and RotateRightV nodes
 - 8257901: ZGC: Take virtual memory usage into account when sizing heap
 - 8257997: sun/security/ssl/SSLSocketImpl/SSLSocketLeak.java again reports leaks after JDK-8257884
 - 8257876: Avoid Reference.isEnqueued in tests
 - 8256459: java/net/httpclient/ManyRequests.java and java/net/httpclient/LineBodyHandlerTest.java fail infrequently with java.net.ConnectException: Connection timed out: no further information
 - 8256730: Code that uses Object.checkIndex() range checks doesn't optimize well
 - ... and 585 more: https://git.openjdk.java.net/portola/compare/33b2207a...fd36fe86

The webrevs contain the adjustments done while merging with regards to each parent branch:
 - master: https://webrevs.openjdk.java.net/?repo=portola&pr=18&range=00.0
 - jdk: https://webrevs.openjdk.java.net/?repo=portola&pr=18&range=00.1

Changes: https://git.openjdk.java.net/portola/pull/18/files
  Stats: 318294 lines in 3017 files changed: 202257 ins; 80680 del; 35357 mod
  Patch: https://git.openjdk.java.net/portola/pull/18.diff
  Fetch: git fetch https://git.openjdk.java.net/portola pull/18/head:pull/18

PR: https://git.openjdk.java.net/portola/pull/18