scd: Fix scd_kick_the_loop.
* scd/scdaemon.c (notify_fd): Remove. (the_event) [W32]: New. (main_thread_pid) [!W32]: New. (handle_signal): Handle SIGCONT. (scd_kick_the_loop): Use signal on UNIX and event on Windows. (handle_connections): Likewise.
Code with CreateEvent is copied from gpg-agent.c.
Code for signal is copied from dkg's gpg-agent-idling in Debian.
- GnuPG-bug-id: T2982
- Signed-off-by: NIIBE Yutaka <gniibe@fsij.org>