Fix #5&: failure to reset socket count on SIGHUP

As reported on GitHub. When logging to a remote host, after a few
SIGHUP's we get the following log message:

     Only 16 IP addresses per socket supported.

When closing all currently open sockets, the socket count must be reset
to allow for opening new ones, otherwise we'll run out of "counts".
Yes, this should be refactored to use the FreeBSD model implementation.

Problem introduced in v2.4.0, commit 075815e.

Signed-off-by: Joachim Wiberg <troglobit@gmail.com>

src/syslogd.c

@@ -2645,6 +2645,7 @@ static void init(void)
 		} else {
 			for (size_t i = 0; i < pe->pe_socknum; i++)
 				socket_close(pe->pe_sock[i]);
+			pe->pe_socknum = 0;
 
 			if (SecureMode < 2)
 				create_inet_socket(pe);