s3: smbd: kernel oplocks. Replace retry_open() with setup_kernel_oplock_poll_open().

s3: smbd: kernel oplocks. Replace retry_open() with setup_kernel_oplock_poll_open().

If a O_NONBLOCK open fails with EWOULDBLOCK, this code changes smbd to
do a retry open every second, until either the timeout or we get a successful
open. If we're opening a file that has a kernel lease set by a non-smbd
process, this is the best we can do.

Prior to this, smbd would block on the second open on such a leased file
(not using O_NONBLOCK) which freezes active clients.

Regression test to follow.

BUG: https://bugzilla.samba.org/show_bug.cgi?id=13121

Signed-off-by: Jeremy Allison <jra@samba.org>
Reviewed-by: Ralph Boehme <slow@samba.org>