in case the user opened a file using the DELETE_ON_CLOSE flag,
return the error code generated in the delete operation.
Note, that this is however just a partial fix to the e_close_1 test
from the ibm testsuite, since the object destructor that triggers
the file_close function does not have a mechanism right now to recognize
and return an error code.
Signed-off-by: Edgar Gabriel <gabriel@cs.uh.edu>