* src/assuan-socket-connect.c (_assuan_connect_finalize): We don't use
FLAGS.
* src/assuan-socket.c (_assuan_sock_get_flag): It's unsigned on
Windows.
(_assuan_sock_get_nonce): We don't use ADDRLEN.
* src/system-w32.c (__assuan_spawn): We don't use ATFORK and
ATFORKVALUE.
* src/system.c (_assuan_socket): We care about ASSUAN_INVALID_FD.