Request for review 8003635: NPG: AsynchGetCallTrace broken by Method* virtual call

[Coleen Phillimore]

Summary: Make metaspace::contains be lock free and used to see if 
something is in metaspace, also compare Method* with vtbl pointer.

open webrev at http://cr.openjdk.java.net/~coleenp/8003635/
bug link at http://bugs.sun.com/view_bug.do?bug_id=8003635

Tested with full NSK testlist on linux 32.  Studio tools group also 
tested this.

Thanks,
Coleen