Subzero: Add -Wshadow to the build.

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 384 matching lines @@
 
 protected:
   void emitGlobal(const VariableDeclaration &Var,
                   const IceString &SectionSuffix);
 
   /// For now, we assume .long is the right directive for emitting 4 byte
   /// emit global relocations. However, LLVM MIPS usually uses .4byte instead.
   /// Perhaps there is some difference when the location is unaligned.
   static const char *getEmit32Directive() { return ".long"; }
 
-  explicit TargetDataLowering(GlobalContext *Ctx) : Ctx(Ctx) {}
+  explicit TargetDataLowering(GlobalContext *MyCtx) : Ctx(MyCtx) {}
   GlobalContext *Ctx;
 };
 
 /// TargetHeaderLowering is used to "lower" the header of an output file.
 /// It writes out the target-specific header attributes. E.g., for ARM
 /// this writes out the build attributes (float ABI, etc.).
 class TargetHeaderLowering {
   TargetHeaderLowering() = delete;
   TargetHeaderLowering(const TargetHeaderLowering &) = delete;
   TargetHeaderLowering &operator=(const TargetHeaderLowering &) = delete;
 
 public:
   static std::unique_ptr<TargetHeaderLowering>
   createLowering(GlobalContext *Ctx);
   virtual ~TargetHeaderLowering();
 
   virtual void lower() {}
 
 protected:
-  explicit TargetHeaderLowering(GlobalContext *Ctx) : Ctx(Ctx) {}
+  explicit TargetHeaderLowering(GlobalContext *MyCtx) : Ctx(MyCtx) {}
   GlobalContext *Ctx;
 };
 
 } // end of namespace Ice
 
 #endif // SUBZERO_SRC_ICETARGETLOWERING_H