BUG/MEDIUM: server: Also copy "check-sni" for server templates.

When using server templates, if "check-sni" is used, make sure it shows up
in all the created servers.

This should be backported to 1.8 and 1.9.
diff --git a/src/server.c b/src/server.c
index 8ca7043..24732b3 100644
--- a/src/server.c
+++ b/src/server.c
@@ -1612,6 +1612,7 @@
 	srv->check.addr = srv->agent.addr = src->check.addr;
 	srv->check.use_ssl            = src->check.use_ssl;
 	srv->check.port               = src->check.port;
+	srv->check.sni                = src->check.sni;
 	/* Note: 'flags' field has potentially been already initialized. */
 	srv->flags                   |= src->flags;
 	srv->do_check                 = src->do_check;