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

src/IceInstX86Base.h

 //===- subzero/src/IceInstX86Base.h - Generic x86 instructions -*- C++ -*--===//
 //
 //                        The Subzero Code Generator
 //
 // This file is distributed under the University of Illinois Open Source
 // License. See LICENSE.TXT for details.
 //
 //===----------------------------------------------------------------------===//
 ///
 /// \file
@@ skipping 2478 matching lines @@
 };
 
 /// Nop instructions of varying length
 template <class Machine> class InstX86Nop final : public InstX86Base<Machine> {
   InstX86Nop() = delete;
   InstX86Nop(const InstX86Nop &) = delete;
   InstX86Nop &operator=(const InstX86Nop &) = delete;
 
 public:
   // TODO: Replace with enum.
-  typedef unsigned NopVariant;
+  using NopVariant = unsigned;
 
   static InstX86Nop *create(Cfg *Func, NopVariant Variant) {
     return new (Func->allocate<InstX86Nop>()) InstX86Nop(Func, Variant);
   }
   void emit(const Cfg *Func) const override;
   void emitIAS(const Cfg *Func) const override;
   void dump(const Cfg *Func) const override;
   static bool classof(const Inst *Inst) {
     return InstX86Base<Machine>::isClassof(Inst, InstX86Base<Machine>::Nop);
   }
@@ skipping 698 matching lines @@
           &InstX86Base<Machine>::Traits::Assembler::psrl};                     \
   }                                                                            \
   }
 
 } // end of namespace X86Internal
 } // end of namespace Ice
 
 #include "IceInstX86BaseImpl.h"
 
 #endif // SUBZERO_SRC_ICEINSTX86BASE_H