opr: Add new queue implementation

opr: Add new queue implementation

Add a new queue implementation for OpenAFS. This has a similar calling
form as the current RX queue implementation, but is implementated using
type safe functions, and supports structures with multiple queue
headers. This permits threading a structure onto multiple queues at the
same time.

The eventual intention is that this queue implementation will replace
both rx_queue and the Unix cache manager afs_q.

Change-Id: I8f815872b017a85eb52a6e6451cdcee3eb869519
Reviewed-on: http://gerrit.openafs.org/3139
Reviewed-by: Derrick Brashear <shadow@dementia.org>
Tested-by: Derrick Brashear <shadow@dementia.org>