r5014: Split out the request to send an async level II oplock break into a

r5014: Split out the request to send an async level II oplock break into a
new function to make it clear when it's called. Remove async parameter
that had been overloaded into request_oplock_break.
Inspired by work from Nadav Danieli <nadavd@exanet.com>.
Jeremy.
(This used to be commit 05697fb50236dfc28e81f8b3900eac17cace57c1)