RFR (S) 8079408 - Improve class loading log (with unified logging)

[Ioi Lam]

Please review a small fix, related to unified logging:

http://cr.openjdk.java.net/~iklam/8079408-improve-class-load-log/

Bug: 8079408 Improve class loading log (with unified logging)

     https://bugs.openjdk.java.net/browse/JDK-8079408

Summary of fix:

     This fix has 2 parts:

     [a] Reimplement TraceClassData and TraceClassLoading as
         -Xlog:classloaderdata and -Xlog:classload
     [b] Add more detailed info to -Xlog:classload so we can perform
         more analysis

     Example:

     java -Xlog:classloaderdata=debug,classload=trace:file=log.txt \
          -cp ~/tests Hello

     I have completely replaced TraceClassData with -Xlog:classloaderdata.
     The TraceClassData flag has been removed from globals.hpp.

     Since many existing tools use TraceClassLoading, I think it's better to
     deprecate it, but otherwise don't change how it works. Instead, we 
add a
     new -Xlog:classload flag that's independent of the old 
TraceClassLoading
     flag.

     (note: the deprecation of TraceClassLoading will be done in a
      separate bug).

     I have also not tied "-verbose:class" with the classload log, since I
     think "-verbose:class" is obsolete and should be replaced by -Xlog.

Tests:

     RBT:

     I ran these testlists using RBT (more than 20000 total classes on
     Linux/Windows/MacOS/solaris) and saw no new failures. I think this 
means
     no existing tests depend on the removed -XX:+TraceClassLoaderData flag.

     hotspot/test/:hotspot_all
     vm.parallel_class_loading.testlist
     vm.regression.testlist
     vm.runtime.testlist
     vm.tmtools.testlist
     nsk.sajdi.testlist
     nsk.stress.testlist
     nsk.stress.jck.testlist
     vm.gc.testlist
     vm.metaspace.testlist

Thanks
- Ioi
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