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/tools/llvm-exegesis/lib/Assembler.cpp b/llvm/tools/llvm-exegesis/lib/Assembler.cpp
index 8118506..30723e5 100644
--- a/llvm/tools/llvm-exegesis/lib/Assembler.cpp
+++ b/llvm/tools/llvm-exegesis/lib/Assembler.cpp
@@ -167,8 +167,8 @@
   TPC->setInitialized();
 
   // AsmPrinter is responsible for generating the assembly into AsmBuffer.
-  if (TM->addAsmPrinter(PM, AsmStream, llvm::TargetMachine::CGFT_ObjectFile,
-                        MCContext))
+  if (TM->addAsmPrinter(PM, AsmStream, nullptr,
+                        llvm::TargetMachine::CGFT_ObjectFile, MCContext))
     llvm::report_fatal_error("Cannot add AsmPrinter passes");
 
   PM.run(*Module); // Run all the passes