s3: smbd : Ensure file_new doesn't call into smbXsrv_open_create() for INTERNAL_OPEN_...

s3: smbd : Ensure file_new doesn't call into smbXsrv_open_create() for INTERNAL_OPEN_ONLY.

This causes deadlocks which cause smbd to crash if the locking
database has already been locked for a compound operation we
need to be atomic (as in the file rename case).

Ensure INTERNAL_OPEN_ONLY opens are synonymous with req==NULL.

INTERNAL_OPEN_ONLY opens leave a NO_OPLOCK record in
the share mode database, so they can be detected by other
processes for share mode violation purposes (because
they're doing an operation on the file that may include
reads or writes they need to have real state inside the
locking database) but have an fnum of FNUM_FIELD_INVALID
and a local share_file_id of zero, as they will never be
seen on the wire.

Ensure validate_my_share_entries() ignores
INTERNAL_OPEN_ONLY records (share_file_id == 0).

Bug 10564 - Lock order violation and file lost

https://bugzilla.samba.org/show_bug.cgi?id=10564

Signed-off-by: Jeremy Allison <jra@samba.org>
Signed-off-by: Volker Lendecke <vl@samba.org>