for-each-ref: introduce 'ref_array_clear()'

Introduce and implement 'ref_array_clear()' which will free
all allocated memory for 'ref_array'.
Mentored-by: NChristian Couder <christian.couder@gmail.com>
Mentored-by: NMatthieu Moy <matthieu.moy@grenoble-inp.fr>
Signed-off-by: NKarthik Nayak <karthik.188@gmail.com>
Reviewed-by: NMatthieu Moy <Matthieu.Moy@imag.fr>
Signed-off-by: NJunio C Hamano <gitster@pobox.com>

builtin/for-each-ref.c

@@ -927,6 +927,26 @@ static int grab_single_ref(const char *refname, const struct object_id *oid,
 	return 0;
 }
 
+/*  Free memory allocated for a ref_array_item */
+static void free_array_item(struct ref_array_item *item)
+{
+	free((char *)item->symref);
+	free(item->refname);
+	free(item);
+}
+
+/* Free all memory allocated for ref_array */
+void ref_array_clear(struct ref_array *array)
+{
+	int i;
+
+	for (i = 0; i < array->nr; i++)
+		free_array_item(array->items[i]);
+	free(array->items);
+	array->items = NULL;
+	array->nr = array->alloc = 0;
+}
+
 static int cmp_ref_sort(struct ref_sort *s, struct ref_array_item *a, struct ref_array_item *b)
 {
 	struct atom_value *va, *vb;
@@ -1157,5 +1177,6 @@ int cmd_for_each_ref(int argc, const char **argv, const char *prefix)
 		maxcount = ref_cbdata.array.nr;
 	for (i = 0; i < maxcount; i++)
 		show_ref(ref_cbdata.array.items[i], format, quote_style);
+	ref_array_clear(&ref_cbdata.array);
 	return 0;
 }