*: fix signedness mix-ups

Signed-off-by: David Lamparter <equinox@opensourcerouting.org>
diff --git a/bgpd/bgp_aspath.c b/bgpd/bgp_aspath.c
index 191a9e7..0aec3ef 100644
--- a/bgpd/bgp_aspath.c
+++ b/bgpd/bgp_aspath.c
@@ -1378,7 +1378,7 @@
 aspath_add_asns (struct aspath *aspath, as_t asno, u_char type, unsigned num)
 {
   struct assegment *assegment = aspath->segments;
-  int i;
+  unsigned i;
 
   if (assegment && assegment->type == type)
     {