[BUG] session: conn_retries was not always initialized

Johannes Smith reported some wrong retries count in logs associated with bad
requests. The cause was that the conn_retries field in the stream interface
was only initialized when attempting to connect, but is used when logging,
possibly with an uninitialized value holding last connection's conn_retries.
This could have been avoided by making use of a stream interface initializer.

This bug is 1.5-specific.
diff --git a/src/proto_http.c b/src/proto_http.c
index 30177ee..ef6f46e 100644
--- a/src/proto_http.c
+++ b/src/proto_http.c
@@ -3987,6 +3987,7 @@
 	s->req->cons->state     = s->req->cons->prev_state = SI_ST_INI;
 	s->req->cons->fd        = -1; /* just to help with debugging */
 	s->req->cons->err_type  = SI_ET_NONE;
+	s->req->cons->conn_retries = 0;  /* used for logging too */
 	s->req->cons->err_loc   = NULL;
 	s->req->cons->exp       = TICK_ETERNITY;
 	s->req->cons->flags     = SI_FL_NONE;
diff --git a/src/session.c b/src/session.c
index 24df936..d673aaa 100644
--- a/src/session.c
+++ b/src/session.c
@@ -188,6 +188,7 @@
 	s->si[1].owner     = t;
 	s->si[1].state     = s->si[1].prev_state = SI_ST_INI;
 	s->si[1].err_type  = SI_ET_NONE;
+	s->si[1].conn_retries = 0;  /* used for logging too */
 	s->si[1].err_loc   = NULL;
 	s->si[1].connect   = NULL;
 	s->si[1].release   = NULL;