gpg: Print export statistics to the status-fd.

* common/status.h (STATUS_EXPORT_RES): New.
* g10/main.h (export_stats_t): New.
* g10/export.c (export_stats_s): New.
(export_new_stats, export_release_stats): New.
(export_print_stats): New.
(export_pubkeys, export_seckeys, export_secsubkeys)
(export_pubkey_buffer, do_export): Add arg "stats".
(do_export_stream): Add arg stats and update it.
* g10/gpg.c (main) <aExport, aExportSecret, aExportSecretSub>: Create,
pass, and print a stats object to the export function calls.

* g10/export.c (export_pubkeys_stream): Remove unused function.

Signed-off-by: Werner Koch <wk@gnupg.org>

doc/DETAILS

@@ -768,6 +768,16 @@ pkd:0:1024:B665B1435F4C2 .... FF26ABB:
     - <not_imported>
     - <skipped_v3_keys>
 
+*** EXPORT_RES <args>
+
+    Final statistics on export process (this is one long line). The
+    args are a list of unsigned numbers separated by white space:
+
+    - <count>
+    - <secret_count>
+    - <exported>
+
+
 ** Smartcard related
 *** CARDCTRL <what> [<serialno>]
     This is used to control smartcard operations.  Defined values for