RFR(S): 8168305 GC.class_stats should not require -XX:+UnlockDiagnosticVMOptions

[Staffan Larsen]

All,

Please review this small patch to remove the requirement -XX:+UnlockDiagnosticVMOptions when running the GC.class_stats diagnostic command. Diagnostic commands are used for diagnosing problems and should not require restarting the JVM with a different command line flag if this can be avoided. 

While fixing this I also noticed that VM.print_touched_methods said it required -XX:+UnlockDiagnosticVMOptions, while what it really required was -XX:+LogTouchedMethods (which in turn requires -XX:+UnlockDiagnosticVMOptions) so I changed the error message here. In this case I think it is ok to require a special command line flag since collecting the information comes with an overhead.

I have verified the fix manually and by running these tests: hotspot/test/runtime/CommandLine/PrintTouchedMethods.java hotspot/test/serviceability/sa/TestInstanceKlassSize.java hotspot/test/serviceability/sa/TestInstanceKlassSizeForInterface.java

bug: https://bugs.openjdk.java.net/browse/JDK-8168305
webrev: http://cr.openjdk.java.net/~sla/8168305/webrev.01/

Thanks,
/Staffan