Propagate const-ness from friend operators

This is not necessary (const-ness would actually apply to some shared
wrapper object, not the wrapped object itself), but made it somewhat
easier to compare with generated code from earlier Qt versions

Author: usiems

generator/abstractmetabuilder.cpp

@@ -262,6 +262,11 @@ void AbstractMetaBuilder::traverseCompareOperator(FunctionModelItem item) {
             if (meta_function != 0 && !meta_function->isInvalid()) {
                 // Strip away first argument, since that is the containing object
                 AbstractMetaArgumentList arguments = meta_function->arguments();
+                if (arguments.front()->type()->isConstant()) {
+                  // propagate constness, though it makes no real difference for the wrapper
+                  // (but I found it helps when comparing to previous results)
+                  meta_function->setConstant(true);
+                }
                 arguments.pop_front();
                 meta_function->setArguments(arguments);