Make these headers as being c++.

llvm-svn: 245050
diff --git a/lld/COFF/Config.h b/lld/COFF/Config.h
index bbaf476..643c493 100644
--- a/lld/COFF/Config.h
+++ b/lld/COFF/Config.h
@@ -1,4 +1,4 @@
-//===- Config.h -----------------------------------------------------------===//
+//===- Config.h -------------------------------------------------*- C++ -*-===//
 //
 //                             The LLVM Linker
 //