Subzero: Fix a build error against LLVM trunk.

src/IceTargetLoweringX86BaseImpl.h

 //===- subzero/src/IceTargetLoweringX86BaseImpl.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 1291 matching lines @@
   InstList::reverse_iterator RI, E;
   for (RI = Insts.rbegin(), E = Insts.rend(); RI != E; ++RI) {
     if (llvm::isa<typename Traits::Insts::Ret>(*RI))
       break;
   }
   if (RI == E)
     return;
 
   // Convert the reverse_iterator position into its corresponding (forward)
   // iterator position.
-  InstList::iterator InsertPoint = RI.base();
+  InstList::iterator InsertPoint = reverseToForwardIterator(RI);
   --InsertPoint;
   Context.init(Node);
   Context.setInsertPoint(InsertPoint);
 
   if (IsEbpBasedFrame) {
     _unlink_bp();
   } else {
     // add stackptr, SpillAreaSizeBytes
     if (SpillAreaSizeBytes != 0) {
       _add_sp(Ctx->getConstantInt32(SpillAreaSizeBytes));
@@ skipping 6767 matching lines @@
         emitGlobal(*Var, SectionSuffix);
       }
     }
   } break;
   }
 }
 } // end of namespace X86NAMESPACE
 } // end of namespace Ice
 
 #endif // SUBZERO_SRC_ICETARGETLOWERINGX86BASEIMPL_H