addtition: Added function declarations

src/arraylist.c

@@ -9,9 +9,10 @@ struct ArrayList{
     size_t capacity;
     size_t len;
     size_t elem_size;
+    size_t borrows;
 };
 
-struct ArrayListSlice {
+struct ArraySlice {
     ArrayList *arr;
     size_t start;
     size_t end;