Use error_code() instead of error_code::succes()

There is no std::error_code::success, so this removes much of the noise
in transitioning to std::error_code.

llvm-svn: 209952
diff --git a/llvm/lib/Support/DataStream.cpp b/llvm/lib/Support/DataStream.cpp
index eec8584..299e6c5 100644
--- a/llvm/lib/Support/DataStream.cpp
+++ b/llvm/lib/Support/DataStream.cpp
@@ -68,7 +68,7 @@
     if (Filename == "-") {
       Fd = 0;
       sys::ChangeStdinToBinary();
-      return error_code::success();
+      return error_code();
     }
 
     return sys::fs::openFileForRead(Filename, Fd);