[backport][7.1.1] RFR: JMC-6554 & JMC-6692

[Alex Macdonald]

Hi everyone,

Please consider these two webrevs [0][1] for backporting the following into
JMC 7:

JMC-6554: Support JFR in OpenJDK 8 [2]
and
JMC-6692: JMC is asking to unlock Commercial Features on JFR enabled
OpenJDK8 [3].

These patches together allow for improved handling of Flight Recordings
with OpenJDK 8. As far as the patches are concerned, JMC-6692 relies on the
changes in 6554, so the patches need to be applied in the order of 6554 ->
6692.

For reference, the original commits can be found at the following links:
JMC-6554:
https://github.com/openjdk/jmc/commit/4b315fe62adb44c5524b55cac2e286fa22324573
JMC-6692:
https://github.com/openjdk/jmc/commit/efc952149024cfb3d92863bd910395946d0beffe

Cheers,

Alex

[0] http://cr.openjdk.java.net/~aptmac/JMC-6554/webrev.01/
[1] http://cr.openjdk.java.net/~aptmac/JMC-6692/webrev.01/
[2] https://bugs.openjdk.java.net/browse/JMC-6554
[3] https://bugs.openjdk.java.net/browse/JMC-6692