Replace llvm::error_code with std::error_code.

llvm-svn: 210780
diff --git a/clang/lib/Serialization/ModuleManager.cpp b/clang/lib/Serialization/ModuleManager.cpp
index ca910be..419d049 100644
--- a/clang/lib/Serialization/ModuleManager.cpp
+++ b/clang/lib/Serialization/ModuleManager.cpp
@@ -104,7 +104,7 @@
       New->Buffer.reset(Buffer);
     } else {
       // Open the AST file.
-      llvm::error_code ec;
+      std::error_code ec;
       if (FileName == "-") {
         ec = llvm::MemoryBuffer::getSTDIN(New->Buffer);
         if (ec)