[jdk11u-dev] RFR: 8267396: Avoid recording "pc" in unhandled oops detector for better performance

[Aleksey Shipilev]

This improves the performance under `-XX:+CheckUnhandledOops`. Backport is unclean, because `Thread::is_in_stack` was renamed to `Thread::is_in_live_stack` by [JDK-8238988](https://bugs.openjdk.java.net/browse/JDK-8238988).

Additional testing:
 - [ ] `tier1` with `-XX:+CheckUnhandledOops`

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Commit messages:
 - 8267396: Avoid recording "pc" in unhandled oops detector for better performance

Changes: https://git.openjdk.java.net/jdk11u-dev/pull/71/files
 Webrev: https://webrevs.openjdk.java.net/?repo=jdk11u-dev&pr=71&range=00
  Issue: https://bugs.openjdk.java.net/browse/JDK-8267396
  Stats: 11 lines in 3 files changed: 0 ins; 3 del; 8 mod
  Patch: https://git.openjdk.java.net/jdk11u-dev/pull/71.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk11u-dev pull/71/head:pull/71

PR: https://git.openjdk.java.net/jdk11u-dev/pull/71