RFR (S): 8140600: Convert unnecessarily malloc'd Monitors to value members

[Thomas Schatzl]

Hi,

On Fri, 2016-02-26 at 23:16 -0500, Derek White wrote:
> This small fix changes a malloc'd monitor into an embedded monitor.
> Also adds assert that no one holds the monitor when we destruct it.
> 
> Bug: https://bugs.openjdk.java.net/browse/JDK-8140600
> Webrev: http://cr.openjdk.java.net/~drwhite/8140600/webrev.01/
> Tests: jprt
> 
> Note: Merged with mgerdin's change to g1YoungRemSetSamplingThread.
> 

  looks good. The .hpp file needs a copyright date fixup.

Thomas