RFR(XL): [JEP-349] 8226511: Implement JFR Event Streaming

[Markus Gronlund]

Greetings,

This is a RFR for JEP 349: JFR Event Streaming [1].

The integration work is tracked under JBS issue 8226511 [2] with associated webrev [3], CSR [4] and JavaDocs [5].

The code includes a demo example [6], provided for convenience to get a taste of what can be built on top of this feature*.
The demo can be activated by starting a regular recording using a specific name, "health", i.e. -XX:StartFlightRecording:name=health

Thank you
Markus and Erik

[1] http://openjdk.java.net/jeps/349 
[2] https://bugs.openjdk.java.net/browse/JDK-8226511 
[3] http://cr.openjdk.java.net/~mgronlun/8226511/v0/webrev/webrev/
[4] https://bugs.openjdk.java.net/browse/JDK-8226512 
[5] http://cr.openjdk.java.net/~mgronlun/8226511/v0/docs/docs/api/jdk.jfr/jdk/jfr/consumer/package-summary.html
[6] http://cr.openjdk.java.net/~egahlin/health-report-agent/health-report-example.txt 
*   The demo example code is only included for convenience, it will be removed later.