fix typos

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@47995 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/AST/DeclSerialization.cpp b/AST/DeclSerialization.cpp
index cb91846..26b36c2 100644
--- a/AST/DeclSerialization.cpp
+++ b/AST/DeclSerialization.cpp
@@ -7,7 +7,7 @@
 //
 //===----------------------------------------------------------------------===//
 //
-//  This files defines methods that implement bitcode serialization for Decls.
+//  This file defines methods that implement bitcode serialization for Decls.
 //
 //===----------------------------------------------------------------------===//