(S) RFR: 8150506: Remove unused locks

[David Holmes]

I stumbled across the fact that the following locks are no longer being 
used in the VM:

Runtime:
  - Interrupt_lock
  - ProfileVM_lock
  - ObjAllocPost_lock

Serviceability:
  -JvmtiPendingEvent_lock

GC:
- CMark_lock
- CMRegionStack_lock

so unless there are objections I will remove them. A reviewer from each 
area would be appreciated.

bug: https://bugs.openjdk.java.net/browse/JDK-8150506

webrev: http://cr.openjdk.java.net/~dholmes/8150506/webrev/

Thanks,
David