Fix -Wunused-but-set-variable warning.

[hokein]

Summary

A follow-up fix on r279958.

[bkramer]

lg. Feel free to submit trivial changes like this without pre-commit review.

llvm/trunk/lib/Target/X86/X86ISelLowering.cpp

static SDValue LowerFABSorFNEG(SDValue Op, SelectionDAG &DAG) {
   bool IsF128 = (VT == MVT::f128);
 
   // FIXME: Use function attribute "OptimizeForSize" and/or CodeGenOpt::Level to
   // decide if we should generate a 16-byte constant mask when we only need 4 or
   // 8 bytes for the scalar case.
 
   MVT LogicVT;
   MVT EltVT;
-  unsigned NumElts;
 
   if (VT.isVector()) {
     LogicVT = VT;
     EltVT = VT.getVectorElementType();
-    NumElts = VT.getVectorNumElements();
   } else if (IsF128) {
     // SSE instructions are used for optimized f128 logical operations.
     LogicVT = MVT::f128;
     EltVT = VT;
-    NumElts = 1;
   } else {
     // There are no scalar bitwise logical SSE/AVX instructions, so we
     // generate a 16-byte vector constant and logic op even for the scalar case.
     // Using a 16-byte mask allows folding the load of the mask with
     // the logic op, so it can save (~4 bytes) on code size.
     LogicVT = (VT == MVT::f64) ? MVT::v2f64 : MVT::v4f32;
     EltVT = VT;
-    NumElts = (VT == MVT::f64) ? 2 : 4;
   }
 
   unsigned EltBits = EltVT.getSizeInBits();
   // For FABS, mask is 0x7f...; for FNEG, mask is 0x80...
   APInt MaskElt =
     IsFABS ? APInt::getSignedMaxValue(EltBits) : APInt::getSignBit(EltBits);
   const fltSemantics &Sem =
       EltVT == MVT::f64 ? APFloat::IEEEdouble :