Fix the g++ build.

src/IceTargetLoweringX86Base.h

 //===- subzero/src/IceTargetLoweringX86Base.h - x86 lowering ----*- C++ -*-===//
 //
 //                        The Subzero Code Generator
 //
 // This file is distributed under the University of Illinois Open Source
 // License. See LICENSE.TXT for details.
 //
 //===----------------------------------------------------------------------===//
 ///
 /// \file
@@ skipping 42 matching lines @@
 ///
 /// but that does not work: the compiler does not know that Machine inherits
 /// from TargetX86Base at this point in translation.
 template <typename TraitsType> class TargetX86Base : public TargetLowering {
   TargetX86Base() = delete;
   TargetX86Base(const TargetX86Base &) = delete;
   TargetX86Base &operator=(const TargetX86Base &) = delete;
 
 public:
   using Traits = TraitsType;
-  using BoolFolding = BoolFolding<Traits>;
   using ConcreteTarget = typename Traits::ConcreteTarget;
   using InstructionSetEnum = typename Traits::InstructionSet;
 
   using BrCond = typename Traits::Cond::BrCond;
   using CmppsCond = typename Traits::Cond::CmppsCond;
 
   using X86Address = typename Traits::Address;
   using X86Operand = typename Traits::X86Operand;
   using X86OperandMem = typename Traits::X86OperandMem;
   using SegmentRegisters = typename Traits::X86OperandMem::SegmentRegisters;
@@ skipping 755 matching lines @@
   typename std::enable_if<T::Is64Bit, void>::type lowerIcmp64(const InstIcmp *,
                                                               const Inst *) {
     llvm::report_fatal_error(
         "Hey, yo! This is x86-64. Watcha doin'? (lowerIcmp64)");
   }
   /// x86lowerIcmp64 handles 64-bit icmp lowering.
   template <typename T = Traits>
   typename std::enable_if<!T::Is64Bit, void>::type
   lowerIcmp64(const InstIcmp *Icmp, const Inst *Consumer);
 
-  BoolFolding FoldingInfo;
+  BoolFolding<Traits> FoldingInfo;
 
   static FixupKind PcRelFixup;
   static FixupKind AbsFixup;
 };
 } // end of namespace X86NAMESPACE
 } // end of namespace Ice
 
 #include "IceTargetLoweringX86BaseImpl.h"
 
 #endif // SUBZERO_SRC_ICETARGETLOWERINGX86BASE_H