RFR: 8359820: Improve handshake/safepoint timeout diagnostic messages [v7]

[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 incrementally with two additional commits since the last revision:

 - 8359820: Addressed reviewer's comments
 - 8359820: Addressed reviewer's comments

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

Changes:
  - all: https://git.openjdk.org/jdk/pull/26309/files
  - new: https://git.openjdk.org/jdk/pull/26309/files/f97067c3..9c914a50

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=26309&range=06
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=26309&range=05-06

  Stats: 13 lines in 3 files changed: 0 ins; 0 del; 13 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