Add CC_Win64ThisCall and set it in the necessary places.

llvm-svn: 126863
diff --git a/clang/lib/CodeGen/CodeGenFunction.h b/clang/lib/CodeGen/CodeGenFunction.h
index ef006d9..25fbd81 100644
--- a/clang/lib/CodeGen/CodeGenFunction.h
+++ b/clang/lib/CodeGen/CodeGenFunction.h
@@ -1126,7 +1126,8 @@
   void StartFunction(GlobalDecl GD, QualType RetTy,
                      llvm::Function *Fn,
                      const FunctionArgList &Args,
-                     SourceLocation StartLoc);
+                     SourceLocation StartLoc,
+                     CallingConv CC);
 
   void EmitConstructorBody(FunctionArgList &Args);
   void EmitDestructorBody(FunctionArgList &Args);