Don't import error_code into the lld namespace.

llvm-svn: 210785
diff --git a/lld/lib/ReaderWriter/Reader.cpp b/lld/lib/ReaderWriter/Reader.cpp
index 355f7e1..f35a9e6 100644
--- a/lld/lib/ReaderWriter/Reader.cpp
+++ b/lld/lib/ReaderWriter/Reader.cpp
@@ -29,7 +29,7 @@
   _yamlHandlers.push_back(std::move(handler));
 }
 
-error_code
+std::error_code
 Registry::parseFile(std::unique_ptr<MemoryBuffer> &mb,
                     std::vector<std::unique_ptr<File>> &result) const {
   // Get file type.