X86: silence a GCC warning

GCC 4.9 gives the following warning:
  warning: enumeral and non-enumeral type in conditional expression
Cast the enumeral value to an integer within the ternary operation.  NFC.

llvm-svn: 227692

llvm/lib/Target/X86/Utils/X86ShuffleDecode.cpp

@@ -429,6 +429,6 @@ void DecodeScalarMoveMask(MVT VT, bool IsLoad, SmallVectorImpl<int> &Mask) {
   unsigned NumElts = VT.getVectorNumElements();
   Mask.push_back(NumElts);
   for (unsigned i = 1; i < NumElts; i++)
-    Mask.push_back(IsLoad ? SM_SentinelZero : i);
+    Mask.push_back(IsLoad ? static_cast<int>(SM_SentinelZero) : i);
 }
 } // llvm namespace