RFR [XS] Subclasses of jdk.jfr.Event loaded from CDS breaks -XX:FlightRecorderOptions=retransform=false

[Ioi Lam]

Please review the follow change:

     https://bugs.openjdk.java.net/browse/JDK-8190191
http://cr.openjdk.java.net/~iklam/jdk10/8190191-jfr-event-retransform-false.v01.open/

Background:

When -XX:FlightRecorderOptions=retransform=false is given in the 
command-line,
subclasses of jdk.jfr.Event are instrumented at load time with 
information that's
specific to the current JVM lifetime. As a result, we cannot perform
such instrumentation at CDS dump time.

A more complicated CDS solution would load these classes from the archive,
and re-do the runtime instrumentation. However, there are only a very
small number of these classes. The performance benefit of archiving them
does not justify the extra complication.

Hence, in this fix, we just identify these classes and exclude them
from the CDS archive during run time.

(Because JFR is still a closed feature, the test cases are in the closed 
repo ...)

Thanks
- Ioi