Fix infinite loop bug in linked list find function.

src/ll.c

@@ -69,6 +69,7 @@ void* ll_find(ll* ll, void* data, compare_func compare) {
     if (compare(data, head->data)) {
       to_return = head->data;
     }
+    head = head->next;
   }
   return to_return;
 }