RFR(s) 8154457: runtime/SharedArchiveFile/SharedStrings Shared string table stats missing

[Jiangli Zhou]

Please review the following change for JDK-8154457 <https://bugs.openjdk.java.net/browse/JDK-8154457>.

  http://cr.openjdk.java.net/~jiangli/8154457/webrev.00/

Added more information when print out message reporting disabling the shared strings at CDS dump time. The shared strings support requires UseG1GC, UseCompressedOops  and UseCompressedClassPointers all to be true. There are cases where the UseCompressedOops and UseCompressedClassPointers options are disabled due to other VM settings. For example, the UseCompressedOops  and UseCompressedClassPointers are turned off if the VM is running in interpreter only mode, or the if MaxHeapSize is too large. The printed message now includes the value of those three options.

Also, handle the cases when shared strings are disabled in SharedStrings.java test.

Thanks,
Jiangli