* g10/key-clean.h (KEY_CLEAN_NONE, KEY_CLEAN_INVALID)
(KEY_CLEAN_ENCR, KEY_CLEAN_AUTHENCR, KEY_CLEAN_ALL): New.
* g10/key-clean.c (clean_one_subkey): New.
(clean_all_subkeys): Add arg CLEAN_LEVEL.
* g10/import.c (import_one): Call clean_all_subkeys with
KEY_CLEAN_NONE.
* g10/export.c (do_export_stream): Call clean_all_subkeys depedning on
the export clean options.