libgit2: missing dependency

[git-bruh]

@mmatongo libgit2 seems to be missing a dependency on cmake. Also nothing actually builds againstlibgit2 (which is only packaged as a static library) due to undefined references symbols provided by zlib, pthread etc. So -lz -lpthread -lcrypto -lssl need to be passed manually (There's nothing in the pkgconfig file either). It works fine without intervention if there's a shared lib available, so maybe that should be enabled aswell.

[mmatongo]

I'll fix the dependency.

Dylan mentioned that nothing builds against libgit2 when I first made the pull for it and the conclusion of that discussion I think was that it was better to have it in the repos and not need it than to need it and not have it.

At the time I was using stagit heavily so it benefited me to have it in the community repos so I didn't have to think too much about it should I reinstall kiss or anything.

[dilyn-corner]

Closed by #304