Add support for Windows cross compile

[NickHu]

A continuation of the work started in #28.

This is essentially bf9af72 but with support for https://github.com/cross-rs/cross.

Testing

1. Install cross
   1a. Install the windows MSVC target as described here: https://github.com/cross-rs/cross-toolchains
2. Download and extract a release from here (e.g. https://github.com/coin-or/Cbc/releases/download/releases%2F2.10.10/Cbc-releases.2.10.10-w64-msvc17-md.zip)
3. CBC_ROOT=<path to extracted Cbc library> cross build --target=x86_64-pc-windows-msvc --example knapsack

[NickHu]

I think #2 is obsolete with respect to this.

@Thell could you please comment on why 9e064a6 exists in #28? It seems to just break things for me.

[Thell]

I think #2 is obsolete with respect to this.

@Thell could you please comment on why 9e064a6 exists in #28? It seems to just break things for me.

I believe that the reason it breaks things for you is that you are using a pre-built release package which, if I remember correctly, does not support parallel and has a libXX naming convention -vs- building from source.
Don't quote me on that since I had quite a adventure trying to get a thread safe windows build up and running on Windows. Even after using Google's prebuilt parallel release I found CBC too slow for what I was working on and ended up using HiGHS which reduced the runtime of my test sets from ~57minutes to ~13minutes and my actual full run from months to days (not to say HiGHS wasn't a problem filled adventure of its own, because it was).