anv: Revive struct anv_common

The struct was deleted by:
  commit efe9d1cde3
  Author: Edward O'Callaghan <funfunctor@folklore1984.net>
  Subject: anv: Clean up some unused variables

Unlike the original anv_common, the new one has a non-const pNext
pointer because we will use it for the output structs of
VK_KHR_get_physical_device_properties2.

v2:
  - Retype pNext from void* to struct anv_common*.

Reviewed-by: Jason Ekstranad <jason@jlekstrand.net>
Reviewed-by: Lionel Landwerlin <lionel.g.landwerlin@intel.com>

src/intel/vulkan/anv_private.h

@@ -1831,6 +1831,11 @@ void anv_dump_finish(void);
 void anv_dump_add_framebuffer(struct anv_cmd_buffer *cmd_buffer,
                               struct anv_framebuffer *fb);
 
+struct anv_common {
+    VkStructureType sType;
+    struct anv_common *pNext;
+};
+
 #define ANV_DEFINE_HANDLE_CASTS(__anv_type, __VkType)                      \
                                                                            \
    static inline struct __anv_type *                                       \