Refer to error_code with the std prefix.

llvm-svn: 210817
diff --git a/clang/lib/Frontend/FrontendActions.cpp b/clang/lib/Frontend/FrontendActions.cpp
index 5147a8a..ef6bfec 100644
--- a/clang/lib/Frontend/FrontendActions.cpp
+++ b/clang/lib/Frontend/FrontendActions.cpp
@@ -310,7 +310,7 @@
 
   // Collect the set of #includes we need to build the module.
   SmallString<256> HeaderContents;
-  std::error_code Err = llvm::error_code();
+  std::error_code Err = std::error_code();
   if (const FileEntry *UmbrellaHeader = Module->getUmbrellaHeader())
     Err = addHeaderInclude(UmbrellaHeader, HeaderContents, CI.getLangOpts(),
                            Module->IsExternC);