Support overriding memory allocation functions

- Let users provide their own memory management functions for XNNPACK

PiperOrigin-RevId: 281355722
diff --git a/test/softargmax-operator-tester.h b/test/softargmax-operator-tester.h
index 1f102a9..906822c 100644
--- a/test/softargmax-operator-tester.h
+++ b/test/softargmax-operator-tester.h
@@ -144,7 +144,7 @@
       }
 
       // Create, setup, run, and destroy SoftArgMax operator.
-      ASSERT_EQ(xnn_status_success, xnn_initialize());
+      ASSERT_EQ(xnn_status_success, xnn_initialize(nullptr /* allocator */));
       xnn_operator_t soft_arg_max_op = nullptr;
 
       ASSERT_EQ(xnn_status_success,