Bug 5578 Followup: Hard Due Dates break hard-coded default circ rule

Bug 5578 Followup: Hard Due Dates break hard-coded default circ rule

If you do not have an applicable circulation rule for a combination of branch,
item type and patron category defined in your Circulation and Fines rules,
the Hard Due Dates development prevents circulation by introducing an error:

Can't call method "output" on an undefined value at /home/magnus/kohahead/C4/Circulation.pm line 2713

This is because the $hardduedate variable is not defined.  Changing the conditional
to check it, rather that it's output, fixes the issue.  That's what this patch does.

Is this the longest commit message for a single line fix?  Maybe.

Signed-off-by: Ian Walls <ian.walls@bywatersolutions.com>
Signed-off-by: Chris Cormack <chrisc@catalyst.net.nz>