anv: Handle null in all destructors

This fixes a bunch of new CTS tests which look for exactly this.  Even in
the cases where we just call vk_free to free a CPU data structure, we still
handle NULL explicitly.  This way we're less likely to forget to handle
NULL later should we actually do something less trivial.

Cc: "13.0" <mesa-stable@lists.freedesktop.org>
Reviewed-by: Dave Airlie <airlied@redhat.com>

src/intel/vulkan/anv_cmd_buffer.c

@@ -262,6 +262,9 @@ void anv_FreeCommandBuffers(
    for (uint32_t i = 0; i < commandBufferCount; i++) {
       ANV_FROM_HANDLE(anv_cmd_buffer, cmd_buffer, pCommandBuffers[i]);
 
+      if (!cmd_buffer)
+         continue;
+
       anv_cmd_buffer_destroy(cmd_buffer);
    }
 }
@@ -758,6 +761,9 @@ void anv_DestroyCommandPool(
    ANV_FROM_HANDLE(anv_device, device, _device);
    ANV_FROM_HANDLE(anv_cmd_pool, pool, commandPool);
 
+   if (!pool)
+      return;
+
    list_for_each_entry_safe(struct anv_cmd_buffer, cmd_buffer,
                             &pool->cmd_buffers, pool_link) {
       anv_cmd_buffer_destroy(cmd_buffer);