[15]: RFR(S): 8241718: assert ((klass)->trace_id()) & ((JfrTraceIdEpoch::method_and_class_in_use_this_epoch_bits()))) != 0 in ObjectSampleCheckpoint::add_to_leakp_set

[Markus Gronlund]

Greetings,

Kindly asking for review for the following change set to fix an interoperability issue between JFR and CDS. 

Bug: https://bugs.openjdk.java.net/browse/JDK-8241718 
Webrev: http://cr.openjdk.java.net/~mgronlun/8241718/webrev00/
Testing: jdk_jfr, runtime/cds

Summary:
General: Method* trace flags should not be serialized to the CDS archive and must therefore be removed in Method::remove_unsharable_info().
JFR specific: CLEAR_METHOD_LEAKP(method) removes the leakp flag on first method write to have it serialize only once.

Thanks
Markus