fix a small memleak in reorder
fix a small memleak in reorder

if set_input was called more than once, it could leak the arrays

thanks @gczuba!

see https://github.com/jcupitt/libvips/issues/607

lovell/libvips,lovell/libvips,jcupitt/libvips,jcupitt/libvips,lovell/libvips,jcupitt/libvips,lovell/libvips,jcupitt/libvips