eliminate some direct access to call stack in legacy class and function objects * pt-eval.h, pt-eval.cc (tree_evaluator::push_stack_frame, tree_evaluator::pop_stack_frame, tree_evaluator::is_class_method_executing, tree_evaluator::is_class_constructor_executing): New functions. * ov-class.cc (octave_class::get_current_method_class, octave_class::in_class_method, Fclass, Fsuperiorto, Finferiorto): Eliminate direct access to call stack. * ov-builtin.cc (octave_builtin::call): Likewise. * ov-fcn-handle.cc (octave_fcn_handle::call, octave_fcn_handle::push_closure_context, make_fcn_handle): Likewise. * ov-mex-fcn.cc (octave_mex_function::call): Likewise.

gnulib = http://hg.octave.org/gnulib