[MINOR] use non-inline tv_* functions in many locations

The __tv_* functions were abused. They are not that small and it is not
always worth using them.
diff --git a/src/backend.c b/src/backend.c
index 002394e..8abaf1c 100644
--- a/src/backend.c
+++ b/src/backend.c
@@ -550,9 +550,7 @@
 			s->srv->cur_sess_max = s->srv->cur_sess;
 	}
 
-	if (tv_isset(&s->be->contimeout))
-		tv_add(&s->req->cex, &now, &s->be->contimeout);
-	else
+	if (!tv_add_ifset(&s->req->cex, &now, &s->be->contimeout))
 		tv_eternity(&s->req->cex);
 	return SN_ERR_NONE;  /* connection is OK */
 }
@@ -680,9 +678,7 @@
 
 	case SRV_STATUS_QUEUED:
 		/* FIXME-20060503 : we should use the queue timeout instead */
-		if (tv_isset(&t->be->contimeout))
-			tv_add(&t->req->cex, &now, &t->be->contimeout);
-		else
+		if (!tv_add_ifset(&t->req->cex, &now, &t->be->contimeout))
 			tv_eternity(&t->req->cex);
 		t->srv_state = SV_STIDLE;
 		/* do nothing else and do not wake any other session up */