Silence a warning

Change-Id: Ie59da76a14c39208356268e601aef3ba6b5d245a
Reviewed-by: Tobias Hunger <tobias.hunger@theqtcompany.com>

src/plugins/cmakeprojectmanager/cmakeproject.cpp

@@ -553,6 +553,7 @@ QStringList CMakeProject::files(FilesMode fileMode) const
             case ProjectExplorer::Project::GeneratedFiles:
                 return isGenerated;
             case ProjectExplorer::Project::AllFiles:
+            default:
                 return true;
             }
         });