memory: Name all the memory listeners

Provide a name field for all the memory listeners.  It can be used to identify
which memory listener is which.

Signed-off-by: Peter Xu <peterx@redhat.com>
Reviewed-by: David Hildenbrand <david@redhat.com>
Message-Id: <20210817013553.30584-2-peterx@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

include/exec/memory.h

@@ -982,6 +982,14 @@ struct MemoryListener {
      */
     unsigned priority;
 
+    /**
+     * @name:
+     *
+     * Name of the listener.  It can be used in contexts where we'd like to
+     * identify one memory listener with the rest.
+     */
+    const char *name;
+
     /* private: */
     AddressSpace *address_space;
     QTAILQ_ENTRY(MemoryListener) link;