r3135: split the "create new" logic out from the "open existing" logic in

r3135: split the "create new" logic out from the "open existing" logic in
pvfs_open, and handle the various race conditions that are inherent in
cifs on unix, so we do the best we can when the race happens.

the ntcreatex code is really starting to take shape now
(This used to be commit 395c3815b468ae55de9a1135e478711f0e7d8cfc)