MINOR: stream_interface: add a client target : TARG_TYPE_CLIENT

This one will be used to identify the direction the SI is being used. All
incoming connections have a target of type TARG_TYPE_CLIENT.
diff --git a/src/session.c b/src/session.c
index 3024599..77fc32e 100644
--- a/src/session.c
+++ b/src/session.c
@@ -173,7 +173,7 @@
 	s->si[0].proto     = l->proto;
 	s->si[0].release   = NULL;
 	s->si[0].send_proxy_ofs = 0;
-	clear_target(&s->si[0].target);
+	set_target_client(&s->si[0].target);
 	s->si[0].exp       = TICK_ETERNITY;
 	s->si[0].flags     = SI_FL_NONE;