Fault: Move the definition of NoFault from faults.hh to fault.hh.

Moving the definition of NoFault into fault.hh doesn't bring any new
dependencies with it, and allows some files to include just fault.hh which has
less baggage. NoFault will still be available to everything that includes
faults.hh because it includes fault.hh.

src/sim/fault.hh

@@ -35,4 +35,6 @@ class FaultBase;
 template <class T> class RefCountingPtr;
 typedef RefCountingPtr<FaultBase> Fault;
 
+FaultBase * const NoFault = 0;
+
 #endif // __SIM_FAULT_HH__

src/sim/faults.hh

@@ -61,8 +61,6 @@ class FaultBase : public RefCounted
     virtual bool isAlignmentFault() const {return false;}
 };
 
-FaultBase * const NoFault = 0;
-
 class UnimpFault : public FaultBase
 {
   private: