Some struct/class mismatch fixes, to silence MSVC warnings.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@66335 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/CodeGen/CodeGenModule.h b/lib/CodeGen/CodeGenModule.h
index 76ab0f8..c3a84af 100644
--- a/lib/CodeGen/CodeGenModule.h
+++ b/lib/CodeGen/CodeGenModule.h
@@ -51,7 +51,7 @@
   class NamedDecl;
   class ValueDecl;
   class VarDecl;
-  struct LangOptions;
+  class LangOptions;
   class Diagnostic;
   class AnnotateAttr;