[jdk11u-dev] RFR: 8279077: JFR crashes on Linux ppc due to missing crash protector in signal handler

[Zhengyu Gu]

I would like to backport this Linux ppc specific bug to 11u.

The patch fixes potential crashes when jfr try to snapshot stacks of other threads.

The JDK15u patch applies cleanly.

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Commit messages:
 - Backport 250ef7dd34d2622864a6d7f92b645405997fad98

Changes: https://git.openjdk.java.net/jdk11u-dev/pull/739/files
 Webrev: https://webrevs.openjdk.java.net/?repo=jdk11u-dev&pr=739&range=00
  Issue: https://bugs.openjdk.java.net/browse/JDK-8279077
  Stats: 4 lines in 1 file changed: 4 ins; 0 del; 0 mod
  Patch: https://git.openjdk.java.net/jdk11u-dev/pull/739.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk11u-dev pull/739/head:pull/739

PR: https://git.openjdk.java.net/jdk11u-dev/pull/739