Bug 6927-- Typo in C4::Overdues.pm

Bug 6927-- Typo in C4::Overdues.pm

Corrected a small typo in overdues.pm to fix a "Undefined subroutine &C4::Members::checkoverdues called at /home/koha/kohaclone/C4/Members.pm line 511." when making calls to GetMemberDetails

This fix suggested by Elliot Davis of UT Tyler, and he did the testing -- I'm just submitting the fix to master for him.  :)

Signed-off-by: Chris Cormack <chrisc@catalyst.net.nz>
(cherry picked from commit 085de44ebdc5bf6431c59b3e60af0277891cd19d)

Signed-off-by: Chris Nighswonger <chris.nighswonger@gmail.com>