RFR: 8359820: Improve handshake/safepoint timeout diagnostic messages [v2]

[Anton Artemov]

> Hi, please consider the following changes:
> 
> The problem in the issue description is not a problem by itself, the behavior is not unexpected, but it is somewhat difficult to find out what caused SIGILL to be fired.
> 
> We propagate this information from `handshake::handle_timeout()` to `VMError::report()` with a help of a global variable.  The same mechanism is used to address a similar issue in the safepoint timeout handler. 
> 
> Tested in tiers 1-3.

Anton Artemov has updated the pull request with a new target base due to a merge or a rebase. The pull request now contains eight commits:

 - Merge remote-tracking branch 'origin/master' into JDK-8359820-SIGILL-with-low-handshake-timeout-on-intel-sde
 - 8359820: Fixed test
 - 8359820: Removed extra line
 - Merge branch 'JDK-8359820-SIGILL-with-low-handshake-timeout-on-intel-sde' of https://github.com/toxaart/jdk into JDK-8359820-SIGILL-with-low-handshake-timeout-on-intel-sde
 - Merge remote-tracking branch 'origin/master' into JDK-8359820-SIGILL-with-low-handshake-timeout-on-intel-sde
 - 8359820:  Improved safepoint and handshake timeout report
 - 8359820: Fixed newline
 - 8359820: Explicitly report SIGILL fired by handshake timeout handler in VMError::report()

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Changes: https://git.openjdk.org/jdk/pull/26309/files
  Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=26309&range=01
  Stats: 21 lines in 5 files changed: 19 ins; 0 del; 2 mod
  Patch: https://git.openjdk.org/jdk/pull/26309.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/26309/head:pull/26309

PR: https://git.openjdk.org/jdk/pull/26309