Eliminate jvmstat dependency on sun.management.counter

jvmstat has references to sun.management.counter.Units and sun.management.counter.Variability classes. We shall eliminate this unnecessary dependency.

sun.jvmstat.monitor.AbstractMonitor -> sun.management.counter.Units (sun.management)
sun.jvmstat.monitor.AbstractMonitor -> sun.management.counter.Variability (sun.management)
sun.jvmstat.monitor.Monitor -> sun.management.counter.Units (sun.management)
sun.jvmstat.monitor.Monitor -> sun.management.counter.Variability (sun.management)
sun.jvmstat.perfdata.monitor.PerfByteArrayMonitor -> sun.management.counter.Units (sun.management)
sun.jvmstat.perfdata.monitor.PerfByteArrayMonitor -> sun.management.counter.Variability (sun.management)
sun.jvmstat.perfdata.monitor.PerfIntegerMonitor -> sun.management.counter.Units (sun.management)
sun.jvmstat.perfdata.monitor.PerfIntegerMonitor -> sun.management.counter.Variability (sun.management)
sun.jvmstat.perfdata.monitor.PerfLongMonitor -> sun.management.counter.Units (sun.management)
sun.jvmstat.perfdata.monitor.PerfLongMonitor -> sun.management.counter.Variability (sun.management)
sun.jvmstat.perfdata.monitor.PerfStringConstantMonitor -> sun.management.counter.Variability (sun.management)
sun.jvmstat.perfdata.monitor.PerfStringMonitor -> sun.management.counter.Units (sun.management)
sun.jvmstat.perfdata.monitor.PerfStringMonitor -> sun.management.counter.Variability (sun.management)
sun.jvmstat.perfdata.monitor.PerfStringVariableMonitor -> sun.management.counter.Variability (sun.management)
sun.jvmstat.perfdata.monitor.v1_0.PerfDataBuffer -> sun.management.counter.Units (sun.management)
sun.jvmstat.perfdata.monitor.v1_0.PerfDataBuffer -> sun.management.counter.Variability (sun.management)
sun.jvmstat.perfdata.monitor.v2_0.PerfDataBuffer -> sun.management.counter.Units (sun.management)
sun.jvmstat.perfdata.monitor.v2_0.PerfDataBuffer -> sun.management.counter.Variability (sun.management)