Serviceability Agent support in JDK9

[Andrew Haley]

I'm having trouble with compiler replay data in JDK 9:

 $ ./build/linux-aarch64-normal-server-slowdebug/jdk/bin/java -Xbootclasspath/p:boot.jar -cp app.jar -XX:ReplayDataFile=replay.foo -XX:+ReplayCompiles
Error occurred during initialization of VM
java/lang/ClassFormatError: Missing BootstrapMethods attribute in class file java/lang/CharSequence

I guess this is because sun.jvm.hotspot.tools.jcore.ClassWriter doesn't
handle the BootstrapMethods attribute.  Is that right?  It would be nice
to have this working.

Andrew.