bug#17149: shred - tape data

[Paul Eggert]

Pádraig Brady wrote:

                    if (! INT_ADD_OVERFLOW (size, size_incr))
                      size += size_incr;
+                  else
+                    size = OFF_T_MAX;

A clearer way to write that would be:

   size += MIN (size_incr, OFF_T_MAX - size);

Otherwise it looks good.