Cherry-pick r234714: [MC] Write padding into fragments when -mc-relax-all flag is used

include/llvm/MC/MCELFStreamer.h

 //===- MCELFStreamer.h - MCStreamer ELF Object File Interface ---*- C++ -*-===//
 //
 //                     The LLVM Compiler Infrastructure
 //
 // This file is distributed under the University of Illinois Open Source
 // License. See LICENSE.TXT for details.
 //
 //===----------------------------------------------------------------------===//
 
 #ifndef LLVM_MC_MCELFSTREAMER_H
@@ skipping 82 matching lines @@
   void EmitBundleAlignMode(unsigned AlignPow2) override;
   void EmitBundleLock(bool AlignToEnd) override;
   void EmitBundleUnlock() override;
 
 private:
   void EmitInstToFragment(const MCInst &Inst, const MCSubtargetInfo &) override;
   void EmitInstToData(const MCInst &Inst, const MCSubtargetInfo &) override;
 
   void fixSymbolsInTLSFixups(const MCExpr *expr);
 
+  /// \brief Merge the content of the fragment \p EF into the fragment \p DF.
+  void mergeFragment(MCDataFragment *, MCEncodedFragmentWithFixups *);
+
   bool SeenIdent;
 
   struct LocalCommon {
     MCSymbolData *SD;
     uint64_t Size;
     unsigned ByteAlignment;
   };
 
   std::vector<LocalCommon> LocalCommons;
 
   SmallPtrSet<MCSymbol *, 16> BindingExplicitlySet;
+
+  /// BundleGroups - The stack of fragments holding the bundle-locked
+  /// instructions.
+  llvm::SmallVector<MCDataFragment *, 4> BundleGroups;
 };
 
 MCELFStreamer *createARMELFStreamer(MCContext &Context, MCAsmBackend &TAB,
                                     raw_ostream &OS, MCCodeEmitter *Emitter,
                                     bool RelaxAll, bool IsThumb);
 
 } // end namespace llvm
 
 #endif