lto/addAsmGlobalSymbols: fail fracefully when the target does not define AsmParser.

lib/Target/PNaCl/PNaClTargetMachine.h

+//===-- PNaClTargetMachine.h - TargetMachine for the PNaCl --*- C++ -*-===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+//
+// This file declares the PNaCl-specific subclass of TargetMachine.
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef PNACLTARGETMACHINE_H
+#define PNACLTARGETMACHINE_H
+
+#include "llvm/Target/TargetMachine.h"
+#include "llvm/Target/TargetData.h"
+
+namespace llvm {
+
+class formatted_raw_ostream;
+
+class PNaClTargetMachine : public TargetMachine {
+  const TargetData DataLayout;       // Calculates type size & alignment
+
+public:
+  PNaClTargetMachine(const Target &T, StringRef TT,
+                   StringRef CPU, StringRef FS,
+                   Reloc::Model RM, CodeModel::Model CM);
+
+  virtual bool addPassesToEmitFile(PassManagerBase &PM,
+                                   formatted_raw_ostream &Out,
+                                   CodeGenFileType FileType,
+                                   CodeGenOpt::Level OptLevel,
+                                   bool DisableVerify);
+
+  virtual const TargetData *getTargetData() const { return &DataLayout; }
+};
+
+extern Target ThePNaClTarget;
+
+} // end namespace llvm
+
+#endif