s3 onefs: Fix a race condition exists in onefs_open.c between multiple opens to the...

s3 onefs: Fix a race condition exists in onefs_open.c between multiple opens to the same file.

Two openers can stat a file at the same time, see that it doesn't exist,
and then both race to open it first.  The loser will enter
onefs_open_file_ntcreate believing that the file doesnt exist, and thus
skip any current state lookups for that file.  This includes setting
the file_id, and having a valid stat buffer.

Normally on first create the file_id will be set during the open, but
the second opener in this scenario may fail the open (oplock/share mode)
and file_id will not be set, nor will the stat buffer be valid.

In the error paths of this patch, we now double check that the file_id
and the stat buffer are valid before doing other operations.