* g10/options.h (EXPORT_REVOCS): New.
* g10/export.c (export_select_filter): New.
(struct export_filter_attic_s): Add field.
(cleanup_export_globals): Cleanup.
(parse_export_options): Add option "export-revocs".
(parse_and_set_export_filter): Parse the select type.
(do_export_revocs): New.
(do_export_stream): Add a way to select things for export.