add -lznz to the nifti test to help win
add -lznz to the nifti test to help win

see https://github.com/jcupitt/libvips/pull/1066

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