fix warnings about wrong format specifiers for size_t

[r28208]

ir/adt/bitset.h

@@ -349,7 +349,7 @@ static inline void bitset_fprint(FILE *file, const bitset_t *bs)
 
 	putc('{', file);
 	for(i = bitset_next_set(bs, 0); i != (size_t)-1; i = bitset_next_set(bs, i + 1)) {
-		fprintf(file, "%s%d", prefix, i);
+		fprintf(file, "%s%lu", prefix, (unsigned long) i);
 		prefix = ",";
 	}
 	putc('}', file);

ir/be/becopyheur4.c

@@ -181,7 +181,7 @@ static void dbg_admissible_colors(const co_mst_env_t *env, const co_mst_irn_t *n
 		fprintf(stderr, "no admissible colors?!?");
 	else {
 		bitset_foreach(node->adm_colors, idx) {
-			fprintf(stderr, " %d", idx);
+			fprintf(stderr, " %lu", (unsigned long) idx);
 		}
 	}
 }