Don't import error_code into the lld namespace.

llvm-svn: 210785
diff --git a/lld/lib/Core/Resolver.cpp b/lld/lib/Core/Resolver.cpp
index 95daed9..3400901 100644
--- a/lld/lib/Core/Resolver.cpp
+++ b/lld/lib/Core/Resolver.cpp
@@ -242,7 +242,7 @@
 
   for (;;) {
     ErrorOr<File &> file = _context.getInputGraph().getNextFile();
-    error_code ec = file.getError();
+    std::error_code ec = file.getError();
     if (ec == InputGraphError::no_more_files)
       return true;
     if (!file) {