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

lib/Target/PNaCl/MCTargetDesc/PNaClMCTargetDesc.cpp

Index: lib/Target/PNaCl/MCTargetDesc/PNaClMCTargetDesc.cpp
===================================================================
--- lib/Target/PNaCl/MCTargetDesc/PNaClMCTargetDesc.cpp	(revision 0)
+++ lib/Target/PNaCl/MCTargetDesc/PNaClMCTargetDesc.cpp	(revision 0)
@@ -0,0 +1,48 @@
+//===-- PNaClMCTargetDesc.cpp - PNaCl Target Descriptions -------*- C++ -*-===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+//
+// This file provides PNaCl specific target descriptions.
+//
+//===----------------------------------------------------------------------===//
+
+#include "PNaClMCTargetDesc.h"
+#include "PNaClMCAsmInfo.h"
+#include "llvm/MC/MCCodeGenInfo.h"
+#include "llvm/MC/MCInstrInfo.h"
+#include "llvm/MC/MCRegisterInfo.h"
+#include "llvm/MC/MCSubtargetInfo.h"
+#include "llvm/Support/TargetRegistry.h"
+
+using namespace llvm;
+
+static MCSubtargetInfo *createPNaClMCSubtargetInfo(StringRef TT, StringRef CPU,
+                                                   StringRef FS) {
+  return new MCSubtargetInfo();
+}
+
+static MCCodeGenInfo *createPNaClMCCodeGenInfo(StringRef TT, Reloc::Model RM,
+                                               CodeModel::Model CM) {
+  MCCodeGenInfo *X = new MCCodeGenInfo();
+  X->InitMCCodeGenInfo(Reloc::PIC_, CM);
+  return X;
+}
+
+// Force static initialization.
+extern "C" void LLVMInitializePNaClTargetMC() {
+  // Register the MC asm info.
+  RegisterMCAsmInfo<PNaClMCAsmInfo> X(ThePNaClTarget);
+
+  // Register the MC codegen info.
+  TargetRegistry::RegisterMCCodeGenInfo(ThePNaClTarget,
+                                        createPNaClMCCodeGenInfo);
+
+  // Register the MC subtarget info.
+  TargetRegistry::RegisterMCSubtargetInfo(ThePNaClTarget,
+                                          createPNaClMCSubtargetInfo);
+}