MINOR: proxy: store the default target into the frontend's configuration

Some services such as peers and CLI pre-set the target applet immediately
during accept(), and for this reason they're forced to have a dedicated
accept() function which does not even properly follow everything the regular
one does (eg: sndbuf/rcvbuf/linger/nodelay are not set, etc).

Let's store the default target when known into the frontend's config so that
it's session_accept() which automatically sets it.
diff --git a/src/dumpstats.c b/src/dumpstats.c
index 8dd9459..50e77ad 100644
--- a/src/dumpstats.c
+++ b/src/dumpstats.c
@@ -234,7 +234,6 @@
  */
 static int stats_accept(struct session *s)
 {
-	s->target = &cli_applet.obj_type;
 	/* no need to initialize the applet, it will start with st0=st1 = 0 */
 
 	tv_zero(&s->logs.tv_request);
@@ -277,6 +276,7 @@
 	fe->conf.file = strdup(file);
 	fe->conf.line = line;
 	fe->accept = stats_accept;
+	fe->default_target = &cli_applet.obj_type;
 
 	/* the stats frontend is the only one able to assign ID #0 */
 	fe->conf.id.key = fe->uuid = 0;
diff --git a/src/peers.c b/src/peers.c
index 1181aae..3fc4882 100644
--- a/src/peers.c
+++ b/src/peers.c
@@ -1096,7 +1096,6 @@
  */
 static int peer_accept(struct session *s)
 {
-	s->target = &peer_applet.obj_type;
 	/* no need to initialize the applet, it will start with st0=st1 = 0 */
 
 	tv_zero(&s->logs.tv_request);
@@ -1126,6 +1125,7 @@
 	fe->conn_retries = CONN_RETRIES;
 	fe->timeout.client = MS_TO_TICKS(5000);
 	fe->accept = peer_accept;
+	fe->default_target = &peer_applet.obj_type;
 	fe->options2 |= PR_O2_INDEPSTR | PR_O2_SMARTCON | PR_O2_SMARTACC;
 }
 
diff --git a/src/session.c b/src/session.c
index 94fc875..7a00b0d 100644
--- a/src/session.c
+++ b/src/session.c
@@ -481,7 +481,7 @@
 		s->si[1].flags |= SI_FL_INDEP_STR;
 
 	session_init_srv_conn(s);
-	s->target = NULL;
+	s->target = p->default_target; /* used by peers and CLI */
 	s->pend_pos = NULL;
 
 	/* init store persistence */