include/queue: Don't allow passing data along with files

include/queue: Don't allow passing data along with files

The queue implementation allows data to be passed along with files in
a queue. This increases the complexity of the queue implementation and
taints the API since the return value from queue_get_file() can't be
used without splitting it first.
This commit removes user-data passing from queue_put_file() and
queue_get_file().