add isRequired

Author: optimisan

llvm/include/llvm/CodeGen/MachineBlockPlacement.h

@@ -36,6 +36,7 @@ class MachineBlockPlacementStatsPass
 public:
   PreservedAnalyses run(MachineFunction &MF,
                         MachineFunctionAnalysisManager &MFAM);
+  static bool isRequired() { return true; }
 };
 
 } // namespace llvm