cmMakefile: Use member directly instead of through method.

This function will not be around much longer anyway.

Source/cmMakefile.cxx

@@ -105,7 +105,7 @@ public:
     ++it;
     if(it == this->VarStack.rend())
       {
-      cmLocalGenerator* plg = mf->GetLocalGenerator()->GetParent();
+      cmLocalGenerator* plg = mf->LocalGenerator->GetParent();
       if(!plg)
         {
         return false;