Pass a reference to a module to the bitcode writer.

This simplifies most callers as they are already using references or
std::unique_ptr.

llvm-svn: 325155
diff --git a/llvm/tools/llvm-modextract/llvm-modextract.cpp b/llvm/tools/llvm-modextract/llvm-modextract.cpp
index b2d21c2..9fd8340 100644
--- a/llvm/tools/llvm-modextract/llvm-modextract.cpp
+++ b/llvm/tools/llvm-modextract/llvm-modextract.cpp
@@ -70,7 +70,7 @@
   }
 
   std::unique_ptr<Module> M = ExitOnErr(Ms[ModuleIndex].parseModule(Context));
-  WriteBitcodeToFile(M.get(), Out->os());
+  WriteBitcodeToFile(*M, Out->os());
 
   Out->keep();
   return 0;