Remove "Adjuststack" instruction opcode.

src/IceInstX86Base.h

 //===- subzero/src/IceInstX86Base.h - Generic x86 instructions -*- C++ -*--===//
 //
 //                        The Subzero Code Generator
 //
 // This file is distributed under the University of Illinois Open Source
 // License. See LICENSE.TXT for details.
 //
 //===----------------------------------------------------------------------===//
 ///
 /// \file
@@ skipping 28 matching lines @@
   using X86TargetLowering = typename Traits::TargetLowering;
 
   enum InstKindX86 {
     k__Start = Inst::Target,
     Adc,
     AdcRMW,
     Add,
     AddRMW,
     Addps,
     Addss,
-    Adjuststack,
     And,
     Andnps,
     Andps,
     AndRMW,
     Blendvps,
     Br,
     Bsf,
     Bsr,
     Bswap,
     Call,
@@ skipping 3305 matching lines @@
           &InstX86Base<Machine>::Traits::Assembler::psrl};                     \
   }                                                                            \
   }
 
 } // end of namespace X86Internal
 } // end of namespace Ice
 
 #include "IceInstX86BaseImpl.h"
 
 #endif // SUBZERO_SRC_ICEINSTX86BASE_H