raw fd close( ) runs more than once from garbage collect

[d-w-moore]

If a trace is put on the following, the PRC will attempt to call close_file on the same object twice.
The problem is apparently avoided if we call the overridden close( ) from iRODSDataObjectRaw's base class sooner, causing the closed property to be set True the first time raw.close( ) is called

import sys
import irods
s = irods.helpers.make_session()
f = s.data_objects.open('/tempZone/home/rods/abcz','w'))
f.write(b'_')