Change costs to be unsigned.

neighbour.c

@@ -256,14 +256,14 @@ reset_txcost(struct neighbour *neigh)
     return 0;
 }
 
-int
+unsigned
 neighbour_txcost(struct neighbour *neigh)
 {
     reset_txcost(neigh);
     return neigh->txcost;
 }
 
-int
+unsigned
 check_neighbours()
 {
     struct neighbour *neigh;
@@ -304,7 +304,7 @@ check_neighbours()
     return msecs;
 }
 
-int
+unsigned
 neighbour_rxcost(struct neighbour *neigh)
 {
     int delay;
@@ -339,7 +339,7 @@ neighbour_rxcost(struct neighbour *neigh)
     }
 }
 
-int
+unsigned
 neighbour_cost(struct neighbour *neigh)
 {
     int a, b;

neighbour.h

@@ -50,7 +50,7 @@ struct neighbour *add_neighbour(const unsigned char *id,
                                 const unsigned char *address,
                                 struct network *net);
 int update_neighbour(struct neighbour *neigh, int hello, int hello_interval);
-int check_neighbours(void);
-int neighbour_txcost(struct neighbour *neigh);
-int neighbour_rxcost(struct neighbour *neigh);
-int neighbour_cost(struct neighbour *neigh);
+unsigned check_neighbours(void);
+unsigned neighbour_txcost(struct neighbour *neigh);
+unsigned neighbour_rxcost(struct neighbour *neigh);
+unsigned neighbour_cost(struct neighbour *neigh);