* agent/gpg-agent.c (get_agent_ssh_socket_name): Use
INVALID_HANDLE_VALUE instead of 0.
(handle_signal) [!HAVE_W32_SYSTEM]: Don't define.
(handle_connections): Port Windows code to NPTH.
* dirmngr/dirmngr.c (handle_connections): Port Windows code to NPTH.
* g13/g13.c (handle_connections): Port Windows code to NPTH.
* scd/scdaemon.c (handle_connections): Port Windows code to NPTH.