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

src/IceTargetLoweringARM32.h

 //===- subzero/src/IceTargetLoweringARM32.h - ARM32 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 TargetLoweringARM32 class, which implements the
@@ skipping 323 matching lines @@
     bool I64InRegs(std::pair<int32_t, int32_t> *Regs);
     bool I32InReg(int32_t *Reg);
 
     static constexpr uint32_t ARM32_MAX_GPR_ARG = 4;
 
   private:
     uint32_t NumGPRRegsUsed;
   };
 
 private:
-  ~TargetARM32() override {}
+  ~TargetARM32() override = default;
 };
 
 class TargetDataARM32 final : public TargetDataLowering {
   TargetDataARM32() = delete;
   TargetDataARM32(const TargetDataARM32 &) = delete;
   TargetDataARM32 &operator=(const TargetDataARM32 &) = delete;
 
 public:
   static std::unique_ptr<TargetDataLowering> create(GlobalContext *Ctx) {
     return std::unique_ptr<TargetDataLowering>(new TargetDataARM32(Ctx));
   }
 
   void lowerGlobals(const VariableDeclarationList &Vars,
                     const IceString &SectionSuffix) override;
   void lowerConstants() override;
 
 protected:
   explicit TargetDataARM32(GlobalContext *Ctx);
 
 private:
-  ~TargetDataARM32() override {}
+  ~TargetDataARM32() override = default;
   template <typename T> static void emitConstantPool(GlobalContext *Ctx);
 };
 
 class TargetHeaderARM32 final : public TargetHeaderLowering {
   TargetHeaderARM32() = delete;
   TargetHeaderARM32(const TargetHeaderARM32 &) = delete;
   TargetHeaderARM32 &operator=(const TargetHeaderARM32 &) = delete;
 
 public:
   static std::unique_ptr<TargetHeaderLowering> create(GlobalContext *Ctx) {
     return std::unique_ptr<TargetHeaderLowering>(new TargetHeaderARM32(Ctx));
   }
 
   void lower() override;
 
 protected:
   explicit TargetHeaderARM32(GlobalContext *Ctx);
 
 private:
   ~TargetHeaderARM32() = default;
 };
 
 } // end of namespace Ice
 
 #endif // SUBZERO_SRC_ICETARGETLOWERINGARM32_H