[time-trace] Add optimizer and codegen regions to NPM

[weiwang]

Summary

Optimizer and codegen regions were only added to legacy PM. Add them to NPM as well.

[myhsu]

LGTM I think this is neat. Thank you!

clang/lib/CodeGen/BackendUtil.cpp

case Backend_EmitLL:
     MPM.addPass(PrintModulePass(*OS, "", CodeGenOpts.EmitLLVMUseLists));
     break;
 
   default:
     break;
   }
 
   // Now that we have all of the passes ready, run them.
+  {
     PrettyStackTraceString CrashInfo("Optimizer");
+    llvm::TimeTraceScope TimeScope("Optimizer");
     MPM.run(*TheModule, MAM);
   }
+}
 
 void EmitAssemblyHelper::RunCodegenPipeline(
     BackendAction Action, std::unique_ptr<raw_pwrite_stream> &OS,
     std::unique_ptr<llvm::ToolOutputFile> &DwoOS) {
   // We still use the legacy PM to run the codegen pipeline since the new PM
   // does not work with the codegen pipeline.
   // FIXME: make the new PM work with the codegen pipeline.
   legacy::PassManager CodeGenPasses;
if (!AddEmitPasses(CodeGenPasses, Action, *OS,
                        DwoOS ? &DwoOS->os() : nullptr))
       // FIXME: Should we handle this error differently?
       return;
     break;
   default:
     return;
   }
 
+  {
     PrettyStackTraceString CrashInfo("Code generation");
+    llvm::TimeTraceScope TimeScope("CodeGenPasses");
     CodeGenPasses.run(*TheModule);
   }
+}
 
 /// A clean version of `EmitAssembly` that uses the new pass manager.
 ///
 /// Not all features are currently supported in this system, but where
 /// necessary it falls back to the legacy pass manager to at least provide
 /// basic functionality.
 ///
 /// This API is planned to have its functionality finished and then to replace