Fix missing arguments in tutorial

In tutorial "8. Kaleidoscope: Compiling to Object Code" a call to
TargetMachine->addPassesToEmitFile(pass, dest, FileType) is missing
nullptr as its 3rd value.

Patch by Sajjad Heydari!

Differential revision: https://reviews.llvm.org/D60369

llvm-svn: 358267
diff --git a/llvm/docs/tutorial/LangImpl08.rst b/llvm/docs/tutorial/LangImpl08.rst
index da4e60f..4f28a2a 100644
--- a/llvm/docs/tutorial/LangImpl08.rst
+++ b/llvm/docs/tutorial/LangImpl08.rst
@@ -157,7 +157,7 @@
   legacy::PassManager pass;
   auto FileType = TargetMachine::CGFT_ObjectFile;
 
-  if (TargetMachine->addPassesToEmitFile(pass, dest, FileType)) {
+  if (TargetMachine->addPassesToEmitFile(pass, dest, nullptr, FileType)) {
     errs() << "TargetMachine can't emit a file of this type";
     return 1;
   }