fixup! addOptInFlag for Flang.cpp too.

Author: madhur13490

clang/lib/Driver/ToolChains/Flang.cpp

@@ -151,8 +151,8 @@ void Flang::addCodegenOptions(const ArgList &Args,
       !stackArrays->getOption().matches(options::OPT_fno_stack_arrays))
     CmdArgs.push_back("-fstack-arrays");
 
-  Args.AddLastArg(CmdArgs, options::OPT_fexperimental_loop_fusion,
-                  options::OPT_fno_experimental_loop_fusion);
+  Args.addOptInFlag(CmdArgs, options::OPT_fexperimental_loop_fusion,
+                    options::OPT_fno_experimental_loop_fusion);
 
   handleInterchangeLoopsArgs(Args, CmdArgs);
   handleVectorizeLoopsArgs(Args, CmdArgs);