[Libguestfs] supermin: how can I avoid downloading packages everytime when run make

[Hu Tao]

Hi,

When I run make in libguestfs directory, supermin tries to redownload
all packages it needs everytime. This is a blocker for me because:

1. I have a slow network connection, redownloading all packages is just
   a waste of time even though they are not big.

2. My network connection is not stable(especially when visiting sites
   outside of China), sometimes it fails to download the packages in the
   middle of downloading, so I have to restart from the beginning.

3. I'm not expected to consume too much network traffic from within
   office.

So what I want to know is:

1. is it possible to use cached packages that supermin already
   downloaded? How?

2. or better, whether supermin can use packages installed on local
   systems, instead of downloading from web?

I read the man page of supermin and saw there is --if-newer and
--use-installed, but I'm not sure how to use them. Any helps will be
appreciated!

Regards,
Hu Tao