We usually prefer snake case for internal/helper functions, but I would also not make this necessarily specific to vkAllocateMemory.
```suggestion:-0+0 static void set_transient_client_handle(struct wine_instance *instance, uint64_t client_handle) ```
(And later we could have `set_transient_client_handle_ptr` to match `add_handle_mapping`/`add_handle_mapping_ptr`)