tools/post: Set permissions on loop device nodes
tools/post: Set permissions on loop device nodes

- Set permissions on loop device nodes during "make postinst".  If the
loop driver is built as a module, udev will do this for us when
openisr-config unloads and reloads the module.  If the driver is built-in,
however, the permissions won't be fixed.  Fixing them ourselves in
postinst prevents the user from having to do it manually or reboot the
machine.

cmusatyalab/openisr,cmusatyalab/openisr,cmusatyalab/openisr,cmusatyalab/openisr,cmusatyalab/openisr