Bug 14566: Fix permissions in patronimage.pl

Bug 14566: Fix permissions in patronimage.pl

There is no permission needed to access the patronimage.pl script.
This means anybody cans access to the patron's images.

Test plan:
Add an image to borrowernumber 42 and call
/cgi-bin/koha/members/patronimage.pl?borrowernumber=42

If you are logged in with borrowers permissions, you will see the image,
otherwise you will get a blank page with a 403 header.

Signed-off-by: Indranil Das Gupta (L2C2 Technologies) <indradg@gmail.com>
Signed-off-by: Katrin Fischer <katrin.fischer.83@web.de>
Signed-off-by: Chris Cormack <chrisc@catalyst.net.nz>