* common/sysutils.h (FD_DBG): New.
* agent/gpg-agent.c (check_nonce): Use FD_DBG.
(do_start_connection_thread, start_connection_thread_ssh): Likewise.
* common/iobuf.c (fd_cache_close, file_filter, do_open): Likewise.
(do_iobuf_fdopen): Likewise.
* dirmngr/dirmngr.c (check_nonce, start_connection_thread)
(handle_connections): Likewise.
* dirmngr/http.c (_my_socket_new, _my_socket_ref): Likewise.
(_my_socket_unref): Likewise.
* g10/decrypt.c (decrypt_message_fd): Likewise.
* g10/encrypt.c (encrypt_crypt): Likewise.
* g10/openfile.c (open_outfile): Likewise.
* g10/plaintext.c (get_output_file, hash_datafile_by_fd): Likewise.
* g10/verify.c (gpg_verify): Likewise.
* kbx/keyboxd.c (check_nonce, do_start_connection_thread): Likewise.
* scd/scdaemon.c (start_connection_thread): Likewise.
(handle_connections): Likewise.
* sm/gpgsm.c (open_es_fread, open_es_fwrite): Likewise.
* tpm2d/tpm2daemon.c (start_connection_thread): Likewise.
(handle_connections): Likewise.