Complete removal of warning about assigning to ancient built-in variables. * libinterp/parse-tree/pt-assign.cc(tree_simple_assignment, tree_multi_assignment): Remove first_execution variable from constructor. * libinterp/parse-tree/pt-assign.cc(rvalue1): Remove setting first_execution. * libinterp/parse-tree/pt-assign.cc(rvalue): Remove setting first_execution. Remove useless loop over lhs for warning about assigning to built-in vars. * libinterp/parse-tree/pt-assign.h(tree_simple_assignment, tree_multi_assignment): Remove first_execution variable from constructors and from private class variable list.