CodeGen: Add a dwo output file argument to addPassesToEmitFile and hook it up to dwo output.

Part of PR37466.

Differential Revision: https://reviews.llvm.org/D47089

llvm-svn: 332881
diff --git a/llvm/lib/CodeGen/ParallelCG.cpp b/llvm/lib/CodeGen/ParallelCG.cpp
index 4624b22..bc3f2a6 100644
--- a/llvm/lib/CodeGen/ParallelCG.cpp
+++ b/llvm/lib/CodeGen/ParallelCG.cpp
@@ -30,7 +30,7 @@
                     TargetMachine::CodeGenFileType FileType) {
   std::unique_ptr<TargetMachine> TM = TMFactory();
   legacy::PassManager CodeGenPasses;
-  if (TM->addPassesToEmitFile(CodeGenPasses, OS, FileType))
+  if (TM->addPassesToEmitFile(CodeGenPasses, OS, nullptr, FileType))
     report_fatal_error("Failed to setup codegen");
   CodeGenPasses.run(*M);
 }