MINOR: servers: Free [idle|safe|priv]_conns on exit.

Don't forget to free idle_conns, safe_conns and priv_conns on exit.

This can be backported to 1.8.
diff --git a/src/haproxy.c b/src/haproxy.c
index b8337b3..54ab7c8 100644
--- a/src/haproxy.c
+++ b/src/haproxy.c
@@ -2408,6 +2408,9 @@
 			free(s->agent.send_string);
 			free(s->hostname_dn);
 			free((char*)s->conf.file);
+			free(s->idle_conns);
+			free(s->priv_conns);
+			free(s->safe_conns);
 
 			if (s->use_ssl || s->check.use_ssl) {
 				if (xprt_get(XPRT_SSL) && xprt_get(XPRT_SSL)->destroy_srv)