gpgme-tool: Fix handling of file descriptors

gpgme-tool: Fix handling of file descriptors

* src/gpgme-tool.c (server_reset_fds): Use close/CloseHandle instead
of the assuan close functions.
(_cmd_decrypt_verify, _cmd_sign_encrypt, cmd_verify, cmd_import)
(cmd_export, cmd_genkey, cmd_getauditlog): Use SERVER object instead
of assuan_get_*_fd functions.
--

Although we used our own handlers for INPUT and OUTPUT, we still used
assuan_get_input_fd, assuan_get_output_fd and their close functions.
That clearly can't work because libassuan does not have any values for
them.