RFR: 8304725: AsyncGetCallTrace can cause SIGBUS on M1 [v2]

[Johannes Bechberger]

> Fixes the issue by transitioning the thread into the WXWrite mode while walking the stack in AsyncGetCallTrace.
> 
> Tested on my M1 mac.

Johannes Bechberger has updated the pull request incrementally with one additional commit since the last revision:

  Make _wx_state volatile

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Changes:
  - all: https://git.openjdk.org/jdk/pull/13144/files
  - new: https://git.openjdk.org/jdk/pull/13144/files/468d71e3..8af25ec0

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=13144&range=01
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=13144&range=00-01

  Stats: 2 lines in 1 file changed: 1 ins; 0 del; 1 mod
  Patch: https://git.openjdk.org/jdk/pull/13144.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/13144/head:pull/13144

PR: https://git.openjdk.org/jdk/pull/13144