Fixed LLControlGroup::get() template to not crash on missing items. Reviewed

by Kelly

indra/llxml/llcontrol.h

@@ -254,6 +254,7 @@ class LLControlGroup : public LLInstanceTracker<LLControlGroup, std::string>
 		else
 		{
 			llwarns << "Control " << name << " not found." << llendl;
+			return T();
 		}
 		return convert_from_llsd<T>(value, type, name);
 	}