Rename last_stmt to last_nondebug_stmt

The following renames last_stmt to last_nondebug_stmt which is
what it really does.

	* tree-cfg.h (last_stmt): Rename to ...
	(last_nondebug_stmt): ... this.
	* tree-cfg.cc (last_stmt): Rename to ...
	(last_nondebug_stmt): ... this.
	(assign_discriminators): Adjust.
	(group_case_labels_stmt): Likewise.
	(gimple_can_duplicate_bb_p): Likewise.
	(execute_fixup_cfg): Likewise.
	* auto-profile.cc (afdo_propagate_circuit): Likewise.
	* gimple-range.cc (gimple_ranger::range_on_exit): Likewise.
	* omp-expand.cc (workshare_safe_to_combine_p): Likewise.
	(determine_parallel_type): Likewise.
	(adjust_context_and_scope): Likewise.
	(expand_task_call): Likewise.
	(remove_exit_barrier): Likewise.
	(expand_omp_taskreg): Likewise.
	(expand_omp_for_init_counts): Likewise.
	(expand_omp_for_init_vars): Likewise.
	(expand_omp_for_static_chunk): Likewise.
	(expand_omp_simd): Likewise.
	(expand_oacc_for): Likewise.
	(expand_omp_for): Likewise.
	(expand_omp_sections): Likewise.
	(expand_omp_atomic_fetch_op): Likewise.
	(expand_omp_atomic_cas): Likewise.
	(expand_omp_atomic): Likewise.
	(expand_omp_target): Likewise.
	(expand_omp): Likewise.
	(omp_make_gimple_edges): Likewise.
	* trans-mem.cc (tm_region_init): Likewise.
	* tree-inline.cc (redirect_all_calls): Likewise.
	* tree-parloops.cc (gen_parallel_loop): Likewise.
	* tree-ssa-loop-ch.cc (do_while_loop_p): Likewise.
	* tree-ssa-loop-ivcanon.cc (canonicalize_loop_induction_variables):
	Likewise.
	* tree-ssa-loop-ivopts.cc (stmt_after_ip_normal_pos): Likewise.
	(may_eliminate_iv): Likewise.
	* tree-ssa-loop-manip.cc (standard_iv_increment_position): Likewise.
	* tree-ssa-loop-niter.cc (do_warn_aggressive_loop_optimizations):
	Likewise.
	(estimate_numbers_of_iterations): Likewise.
	* tree-ssa-loop-split.cc (compute_added_num_insns): Likewise.
	* tree-ssa-loop-unswitch.cc (get_predicates_for_bb): Likewise.
	(set_predicates_for_bb): Likewise.
	(init_loop_unswitch_info): Likewise.
	(hoist_guard): Likewise.
	* tree-ssa-phiopt.cc (match_simplify_replacement): Likewise.
	(minmax_replacement): Likewise.
	* tree-ssa-reassoc.cc (update_range_test): Likewise.
	(optimize_range_tests_to_bit_test): Likewise.
	(optimize_range_tests_var_bound): Likewise.
	(optimize_range_tests): Likewise.
	(no_side_effect_bb): Likewise.
	(suitable_cond_bb): Likewise.
	(maybe_optimize_range_tests): Likewise.
	(reassociate_bb): Likewise.
	* tree-vrp.cc (rvrp_folder::pre_fold_bb): Likewise.