RFR: Merge jdk

[Mikael Vidstedt]

Merge in jdk-16+36

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Commit messages:
 - Merge jdk
 - 8260709: C2: assert(false) failed: unscheduable graph
 - 8260585: AArch64: Wrong code generated for shifting right and accumulating four unsigned short integers
 - 8259794: Remove EA from JDK 16 version string starting with Initial RC promotion on Feb 04, 2021(B35)
 - 8260704: ParallelGC: oldgen expansion needs release-store for _end
 - 8260927: StringBuilder::insert is incorrect without Compact Strings
 - 8258378: Final nroff manpage update for JDK 16
 - 8257215: JFR: Events dropped when streaming over a chunk rotation
 - 8260473: [vector] ZGC: VectorReshape test produces incorrect results with ZGC enabled
 - 8260632: Build failures after JDK-8253353
 - ... and 26 more: https://git.openjdk.java.net/portola/compare/cd53d90e...ae6f6360

The merge commit only contains trivial merges, so no merge-specific webrevs have been generated.

Changes: https://git.openjdk.java.net/portola/pull/22/files
  Stats: 4590 lines in 133 files changed: 4030 ins; 282 del; 278 mod
  Patch: https://git.openjdk.java.net/portola/pull/22.diff
  Fetch: git fetch https://git.openjdk.java.net/portola pull/22/head:pull/22

PR: https://git.openjdk.java.net/portola/pull/22