nc_sendv_compat has a huge stack usage of 69680 bytes approx.
Moving large arrays to heap to reduce stack usage.
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
Signed-off-by: Pooja Dhannawat <dhannawatpooja1@gmail.com>
Signed-off-by: Jason Wang <jasowang@redhat.com>