gpg: Use a common filter_getval for import and export.
* g10/import.c (filter_getval): Rename to ... (impex_filter_getval): this. Make global. (apply_keep_uid_filter, apply_drop_sig_filter): Adjust. * g10/export.c (filter_getval): Remove. (apply_drop_sig_filter): Use impex_filter_getval.
- Signed-off-by: Werner Koch <wk@gnupg.org>