Bugfix: Free bin2hex output in __update_block_title

miner.c

@@ -1695,6 +1695,7 @@ void __update_block_title(const unsigned char *hash_swap)
 		current_hash = malloc(3 /* ... */ + 16 /* block hash segment */ + 1);
 		tmp = bin2hex(&hash_swap[24], 8);
 		sprintf(current_hash, "...%s", tmp);
+		free(tmp);
 		known_blkheight_current = false;
 	} else if (likely(known_blkheight_current)) {
 		return;