RFR: 8364735: [asan] heap-use-after-free error detected in defaultStream::writer during VM shutdown [v2]

[David Holmes]

> `ostream_exit` was deleting the stream underlying the `xtty` prior to nulling the `xtty` global variable, resulting in a use-after-free-error. Due to races during VM shutdown we cannot make use of `xtty` perfectly safe, but we can certainly narrow the window during which use-after-free is possible.
> 
> Testing:
>  - tiers 1-3 sanity
> 
> Thanks

David Holmes 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 two additional commits since the last revision:

 - Merge branch 'master' into 8364735-xtty
 - 8364735: [asan] heap-use-after-free error detected in defaultStream::writer during VM shutdown

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

Changes:
  - all: https://git.openjdk.org/jdk/pull/26832/files
  - new: https://git.openjdk.org/jdk/pull/26832/files/212b6d5a..7cc72240

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=26832&range=01
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=26832&range=00-01

  Stats: 21651 lines in 625 files changed: 14641 ins; 4501 del; 2509 mod
  Patch: https://git.openjdk.org/jdk/pull/26832.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/26832/head:pull/26832

PR: https://git.openjdk.org/jdk/pull/26832