Changing the way saclib builds?

[Nilesh Patra <nilesh@nileshpatra.info>]

Hi Doug,

I was trying to make saclib cross-buildable but I noticed that due
to absence of a build system, it uses libtool off directly; and the standard way of
propagating CC (to get cross builds going)
doesn't go well with the same, see[1]

And so, I have written a Makefile for the same - seems to work. I have committed that to salsa,
if you could take a look and give me an ACK, can I Team-upload?

[1]: https://lists.debian.org/debian-cross/2022/07/msg00008.html

--
Best,
Nilesh