* ui-out.c (struct ui_out_table): Add field entry_level.

* ui-out.c (struct ui_out_table): Add field entry_level.
(verify_field): New function.
(verify_field_proper_position): Delete function.
(verify_field_alignment): Delete function.
(ui_out_field_int): Update to use verify_field.
(ui_out_field_skip): Ditto.
(ui_out_field_string): Ditto.
(ui_out_field_fmt): Ditto.
(ui_out_table_begin): Initialize table.entry_level.
(ui_out_table_end): Clear table.entry_level.
(ui_out_begin): Call verify_field before pushing the new tuple or
list onto the stack.  Use table.entry_level.