FIX: valueMatch for a SMProxyProperty with no proxies returns false

Change-Id: I40d46f6f85b455533560052a6411d60dc5c54aa0
SMProxyProperty::RemoveAllProxies results in a pqGenericPropertyWidgetDecorator::updateState which tries to evaluate valueMatch. This function failed before this fix.
Merge topic 'macro-warning-14970' into next

b39ffc1e FIX: valueMatch for a SMProxyProperty with no proxies returns false