gunit: Update test 009 to better test dirty flag

gunit: Update test 009 to better test dirty flag

When the dirty flag is set, cgroup_set_values_recursive()
was erroneously failing the recursive setting of values.
There were two problems in the unit test that caused this to
be missed:
    1. The dirty flag wasn't being set
    2. If fgets() returned a NULL ptr, the contents of the
       settings file weren't being checked

Reported-by: Bharani viswas <bharani.viswas@gmail.com>
Signed-off-by: Tom Hromatka <tom.hromatka@oracle.com>