gpg: Change pinentry prompt to talk about "secret key".
* g10/passphrase.c (gpg_format_keydesc): Add mode 2. Change strings. * g10/keydb.h (FORMAT_KEYDESC_NORMAL, FORMAT_KEYDESC_IMPORT) (FORMAT_KEYDESC_EXPORT): New. Use them for clarity.
The use of the term "certificate" was more confusing than helpful.