RFR: 8342682: Errors related to unused code on Windows after 8339120 in dt_shmem jdwp security and jpackage [v7]

[Julian Waters]

> After 8339120, gcc began catching many different instances of unused code in the Windows specific codebase. Some of these seem to be bugs. I've taken the effort to mark out all the relevant globals and locals that trigger the unused warnings and addressed all of them by commenting out the code as appropriate. I am confident that in many cases this simplistic approach of commenting out code does not fix the underlying issue, and the warning actually found a bug that should be fixed. In these instances, I will be aiming to fix these bugs with help from reviewers, so I recommend anyone reviewing who knows more about the code than I do to see whether there is indeed a bug that needs fixing in a different way than what I did

Julian Waters 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 branch 'openjdk:master' into unused
 - Neater warning silencer in proc_md.h
 - Revert _WIN32 workaround in log_messages.c
 - Copyright in VersionInfo.cpp
 - Remove neutralLangId in VersionInfo.cpp
 - Remove global memHandle, would've liked to keep it as a comment :(
 - Merge branch 'master' into unused
 - 8342682

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

Changes:
  - all: https://git.openjdk.org/jdk/pull/21616/files
  - new: https://git.openjdk.org/jdk/pull/21616/files/5e9039fb..53036a65

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=21616&range=06
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=21616&range=05-06

  Stats: 200965 lines in 1998 files changed: 125072 ins; 52904 del; 22989 mod
  Patch: https://git.openjdk.org/jdk/pull/21616.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/21616/head:pull/21616

PR: https://git.openjdk.org/jdk/pull/21616