b=2339

b=2339
filter_precreate() was setting the oid returned based on the last_id for the
requested object group, but was always creating objects in group 0 by virtue of
passing NULL in as the obdo to the _next_id functions.  In the process of
fixing this we stop NULLing out the obdo in the loop and get rid of the
_setattr() and obdo_from_inode() which are artifacts from when the client
performed obd_create().

Also some cleanup_phase beautification.