Subzero: Add -Wshadow to the build.

src/IceAPInt.h

 //===-- subzero/src/IceAPInt.h - Constant integer conversions --*- C++ -*--===//
 //
 //                     The LLVM Compiler Infrastructure
 //
 // This file is distributed under the University of Illinois Open Source
 // License. See LICENSE.TXT for details.
 //
 //===----------------------------------------------------------------------===//
 ///
 /// \file
@@ skipping 13 matching lines @@
 
 class APInt {
   APInt() = delete;
   APInt(const APInt &) = delete;
   APInt &operator=(const APInt &) = delete;
 
 public:
   /// Bits in an (internal) value.
   static const SizeT APINT_BITS_PER_WORD = sizeof(uint64_t) * CHAR_BIT;
 
-  APInt(SizeT Bits, uint64_t Val) : BitWidth(Bits), Val(Val) {
+  APInt(SizeT Bits, uint64_t MyVal) : BitWidth(Bits), Val(MyVal) {
     assert(Bits && "bitwidth too small");
     assert(Bits <= APINT_BITS_PER_WORD && "bitwidth too big");
     clearUnusedBits();
   }
 
   uint32_t getBitWidth() const { return BitWidth; }
 
   int64_t getSExtValue() const {
     return static_cast<int64_t>(Val << (APINT_BITS_PER_WORD - BitWidth)) >>
            (APINT_BITS_PER_WORD - BitWidth);
@@ skipping 12 matching lines @@
       return;
 
     // Mask out the high bits.
     Val &= ~static_cast<uint64_t>(0) >> (APINT_BITS_PER_WORD - BitWidth);
   }
 };
 
 } // end of namespace Ice
 
 #endif // SUBZERO_SRC_ICEAPINT_H