Subzero: Use more "= default;" for ctors and dtors.

src/IceTargetLoweringMIPS32.h

 //===- subzero/src/IceTargetLoweringMIPS32.h - MIPS32 lowering ---*- C++-*-===//
 //
 //                        The Subzero Code Generator
 //
 // This file is distributed under the University of Illinois Open Source
 // License. See LICENSE.TXT for details.
 //
 //===----------------------------------------------------------------------===//
 //
 // This file declares the TargetLoweringMIPS32 class, which implements the
@@ skipping 106 matching lines @@
 
   bool UsesFramePointer = false;
   bool NeedsStackAlignment = false;
   llvm::SmallBitVector TypeToRegisterSet[IceType_NUM];
   llvm::SmallBitVector ScratchRegs;
   llvm::SmallBitVector RegsUsed;
   VarList PhysicalRegisters[IceType_NUM];
   static IceString RegNames[];
 
 private:
-  ~TargetMIPS32() override {}
+  ~TargetMIPS32() override = default;
 };
 
 class TargetDataMIPS32 final : public TargetDataLowering {
   TargetDataMIPS32() = delete;
   TargetDataMIPS32(const TargetDataMIPS32 &) = delete;
   TargetDataMIPS32 &operator=(const TargetDataMIPS32 &) = delete;
 
 public:
   static std::unique_ptr<TargetDataLowering> create(GlobalContext *Ctx) {
     return std::unique_ptr<TargetDataLowering>(new TargetDataMIPS32(Ctx));
   }
 
   void lowerGlobals(const VariableDeclarationList &Vars,
                     const IceString &SectionSuffix) override;
   void lowerConstants() override;
 
 protected:
   explicit TargetDataMIPS32(GlobalContext *Ctx);
 
 private:
-  ~TargetDataMIPS32() override {}
+  ~TargetDataMIPS32() override = default;
   template <typename T> static void emitConstantPool(GlobalContext *Ctx);
 };
 
 class TargetHeaderMIPS32 final : public TargetHeaderLowering {
   TargetHeaderMIPS32() = delete;
   TargetHeaderMIPS32(const TargetHeaderMIPS32 &) = delete;
   TargetHeaderMIPS32 &operator=(const TargetHeaderMIPS32 &) = delete;
 
 public:
   static std::unique_ptr<TargetHeaderLowering> create(GlobalContext *Ctx) {
     return std::unique_ptr<TargetHeaderLowering>(new TargetHeaderMIPS32(Ctx));
   }
 
 protected:
   explicit TargetHeaderMIPS32(GlobalContext *Ctx);
 
 private:
   ~TargetHeaderMIPS32() = default;
 };
 
 } // end of namespace Ice
 
 #endif // SUBZERO_SRC_ICETARGETLOWERINGMIPS32_H