Releasing a fence, whose payload has been exported to an external handle using reference transference and later imported to >=1 fences, does not trigger any warning

[DominikWitczakAMD]

Releasing such a "master" fence whose payload is being used by other active fence instances within a process renders remaining fences either hopelessly useless (in case of permanent import) or useless until reset (in case of temporary import). In case of the former, this probably deserves a warning.