Sudoers.pm:Fix hash as ref deprecated issue

Older versions of perl (v5.8.8 for AIX) had an issue with using a hash ref as
the param for keys. Fixed by "casting" it to an actual hash.

Error:

Using a hash as a reference is deprecated at .../liblinux/Sudoers.pm line 154.
Type of arg 1 to keys must be hash (not hash element) at
.../liblinux/Sudoers.pm line 143, near "} )"