Provide an option that holds off queueing indefinitely while the lock
owner is preempted. This could reduce queueing latencies for very
overcommitted vcpu situations.

This is disabled by default.
Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20221126095932.1234527-16-npiggin@gmail.com