jcmd VM.metaspace should report unlimited size if MaxMetaspaceSize isn't specified

When MaxMetaspaceSize is not specified, it would set to max_uintx, jcmd VM.metaspace reports metaspace summary information as follows:

$ ./jcmd <pid> VM.metaspace | grep MaxMetaspaceSize
MaxMetaspaceSize: 17179869184.00 GB

Actually this is a bug, the expected output should be:

MaxMetaspaceSize: unlimited

The root cause of the problem is that the MaxMetaspaceSize rounding performed during arguments parsing is inconsistent with the rounding check in print_settings(metaspaceRerporter.cpp).