RFR: 8270091: The path of JFR emergency dump should be able to specified by the user

[Yasumasa Suenaga]

JFR will dump the recording to the file as hs_err_pid<PID>.jfr if JVM encountered fatal errors (e.g. crash). It will be dumped to current directory, and we cannot specify dump path.

In other dumps (hs_err log, heap dump, replay & inline data for JIT) can be specified it.

This is useful especially in the container application if we can specify it in JFR.

I've filed [CSR](https://bugs.openjdk.java.net/browse/JDK-8270093) for this RFE, please review it too.

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Commit messages:
 - 8270091: The path of JFR emergency dump should be able to specified by the user

Changes: https://git.openjdk.java.net/jdk/pull/4724/files
 Webrev: https://webrevs.openjdk.java.net/?repo=jdk&pr=4724&range=00
  Issue: https://bugs.openjdk.java.net/browse/JDK-8270091
  Stats: 13 lines in 2 files changed: 12 ins; 0 del; 1 mod
  Patch: https://git.openjdk.java.net/jdk/pull/4724.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk pull/4724/head:pull/4724

PR: https://git.openjdk.java.net/jdk/pull/4724