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

lib/Target/PNaCl/PNaClTargetMachine.cpp

+//===-- PNaClTargetMachine.cpp - Define TargetMachine for PNaCl -----------===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+//
+//
+//===----------------------------------------------------------------------===//
+
+#include "PNaCl.h"
+#include "PNaClTargetMachine.h"
+#include "llvm/PassManager.h"
+#include "llvm/Support/FormattedStream.h"
+#include "llvm/Support/TargetRegistry.h"
+using namespace llvm;
+
+extern "C" void LLVMInitializePNaClTarget() {
+  // HACK: this code is needed to claim using at least one symbol
+  // from libLLVMPNaClDesc to help to inlude this dependency into
+  // LibDeps.txt, because it's implicitly implied by llc and Clang.
+  long long a = (long long)(void*)&ThePNaClTarget;
+  if (a*a < 1) {
+    LLVMInitializePNaClTargetMC();
+  }
+  // Register the target.
+  RegisterTargetMachine<PNaClTargetMachine> X(ThePNaClTarget);
+}
+
+PNaClTargetMachine::PNaClTargetMachine(const Target &T, StringRef TT,
+                                       StringRef CPU, StringRef FS,
+                                       Reloc::Model RM, CodeModel::Model CM)
+  : TargetMachine(T, TT, CPU, FS),
+    DataLayout("e-i1:8:8-i8:8:8-i16:16:16-i32:32:32-i64:64:64-f32:32:32-"
+               "f64:64:64-p:32:32:32") {
+  AsmInfo = T.createMCAsmInfo(TT);
+}
+
+//===----------------------------------------------------------------------===//
+//                       External Interface declaration
+//===----------------------------------------------------------------------===//
+
+bool PNaClTargetMachine::addPassesToEmitFile(PassManagerBase &PM,
+                                           formatted_raw_ostream &o,
+                                           CodeGenFileType FileType,
+                                           CodeGenOpt::Level OptLevel,
+                                           bool DisableVerify) {
+  return true;
+}