Use this flag to make the compiler warning go away.

Incidentally, when the flag is false we'll throw an argument error.
We need to implement it properly later.

Change-Id: I70f8b6bac3cf8ad1dae67efc65a9ab16e099253e

sc/source/core/tool/interpr1.cxx

@@ -6587,7 +6587,7 @@ void ScInterpreter::ScSubTotal()
             nFunc -= 100;
         }
 
-        if( nFunc < 1 || nFunc > 11 )
+        if (nFunc < 1 || nFunc > 11 || !bIncludeHidden)
             PushIllegalArgument();  // simulate return on stack, not SetError(...)
         else
         {