Refactor all instances of `typedef y x` to the C++11 `using x = y` syntax.

src/IceTargetLowering.h

 //===- subzero/src/IceTargetLowering.h - Lowering interface -----*- C++ -*-===//
 //
 //                        The Subzero Code Generator
 //
 // This file is distributed under the University of Illinois Open Source
 // License. See LICENSE.TXT for details.
 //
 //===----------------------------------------------------------------------===//
 ///
 /// \file
@@ skipping 188 matching lines @@
   LoweringContext &getContext() { return Context; }
 
   enum RegSet {
     RegSet_None = 0,
     RegSet_CallerSave = 1 << 0,
     RegSet_CalleeSave = 1 << 1,
     RegSet_StackPointer = 1 << 2,
     RegSet_FramePointer = 1 << 3,
     RegSet_All = ~RegSet_None
   };
-  typedef uint32_t RegSetMask;
+  using RegSetMask = uint32_t;
 
   virtual llvm::SmallBitVector getRegisterSet(RegSetMask Include,
                                               RegSetMask Exclude) const = 0;
   virtual const llvm::SmallBitVector &getRegisterSetForType(Type Ty) const = 0;
   virtual const llvm::SmallBitVector &getAliasesForRegister(SizeT) const = 0;
 
   void regAlloc(RegAllocKind Kind);
 
   virtual void
   makeRandomRegisterPermutation(llvm::SmallVectorImpl<int32_t> &Permutation,
@@ skipping 236 matching lines @@
   virtual void lower() {}
 
 protected:
   explicit TargetHeaderLowering(GlobalContext *Ctx) : Ctx(Ctx) {}
   GlobalContext *Ctx;
 };
 
 } // end of namespace Ice
 
 #endif // SUBZERO_SRC_ICETARGETLOWERING_H