[lworld] FYI: Merge jdk

[David Simms]

Merge jdk-15+20

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Commit messages:
 - Whitespace
 - Merge tag 'jdk-15+20' into lworld_merge_jdk_15_20
 - Merge commit '7cc137105928ec109a29d9315565f7f49af3cf2b' into lworld_merge_jdk_15_20
 - Merge commit '642041adbcaa496a10c266c6dbfe9b1b7c670419' into lworld_merge_jdk_15_20
 - 8243210: ClhsdbScanOops fails with NullPointerException in FileMapHeader.inCopiedVtableSpace
 - 8243323: Shenandoah: Recycle immediate garbage before concurrent class unloading
 - 8243200: Shenandoah: Allow concurrent nmethod iteration
 - 8243408: Inconsistent Exceptions are thrown by MulticastSocket when sending a DatagramPacket to port 0
 - 8239365: ProcessBuilder test modifications for AIX execution
 - 8243254: Examine ZipFile slash optimization for non-ASCII compatible charsets
 - ... and 83 more: https://git.openjdk.java.net/valhalla/compare/1e7ad541...045aba00

The webrevs contain the adjustments done while merging with regards to each parent branch:
 - lworld: https://webrevs.openjdk.java.net/valhalla/63/webrev.00.0
 - jdk: https://webrevs.openjdk.java.net/valhalla/63/webrev.00.1

Changes: https://git.openjdk.java.net/valhalla/pull/63/files
  Stats: 767398 lines in 4033 files changed: 16316 ins; 747144 del; 3938 mod
  Patch: https://git.openjdk.java.net/valhalla/pull/63.diff
  Fetch: git fetch https://git.openjdk.java.net/valhalla pull/63/head:pull/63

PR: https://git.openjdk.java.net/valhalla/pull/63