RFR: 8327114: Attach in Linux may have wrong behaviour when pid == ns_pid (Kubernetes debug container) [v7]

[Sebastian Lövdahl]

> 8327114: Attach in Linux may have wrong behaviour when pid == ns_pid (Kubernetes debug container)

Sebastian Lövdahl has updated the pull request with a new target base due to a merge or a rebase. The incremental webrev excludes the unrelated changes brought in by the merge/rebase. The pull request contains eight additional commits since the last revision:

 - Merge remote-tracking branch 'upstream/master' into 8327114-attach-from-container-to-container
 - Clarify PID 1 check with comment
 - Adapt code style
 - Add test for the elevated privileges case
 - Remove unused `SELF_PID_NS`
 - Rewrite in line with suggestion from Larry Cable
 - Reworked attach logic
 - 8327114: Attach in Linux may have wrong behaviour when pid == ns_pid (Kubernetes debug container)

-------------

Changes:
  - all: https://git.openjdk.org/jdk/pull/19055/files
  - new: https://git.openjdk.org/jdk/pull/19055/files/543036bf..0afbf5d2

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=19055&range=06
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=19055&range=05-06

  Stats: 454094 lines in 5932 files changed: 339433 ins; 77948 del; 36713 mod
  Patch: https://git.openjdk.org/jdk/pull/19055.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/19055/head:pull/19055

PR: https://git.openjdk.org/jdk/pull/19055